mac longtubes

[vristang]

Backpressure is not the problem, you dont want excessive backpressure. but you do need enough pressure to keep the exhaust gasses flowing. too large exhaust will allow air to cool and become stagnant inside the system.

Think logically about what you are saying here...
You are telling me that in order to increase airflow, you need to have resistance to airflow.
You are saying that airflow improves when airflow is restricted

yes you proved a viper made an improvement with a 3" exhaust but put on a 4" or 5" and i bet it will be a dissapointment without other mods. so im pretty sure a 2.5" system will be enough for a 250-350hp v8.

sorry there are no proof in numbers here, but the physical explanation is enough for me to believe

So when it is PROVEN that 3" makes more power than 2.5",
You guys change your argument that 4" will kill power.
Amazing.


How in the world can you BELIEVE something without ANY data to support it. This is not a religion, where faith is required.
We are talking about some pretty basic physics concepts here...

The air intake system and exhaust system work together, the exhaust system can only put out what the air intake system can pull in. they need to be sized in relation to each other.

Too big (diameter) exhaust systems can hurt power/torque if the intake system cant match the volume of air to keep the exhaust system flowing. Air, like gas is a fliud, it has fluid properties and will cool down(and contract) in an excessively large exhaust sytem. As the air cools, it will become dense and heavier, than hot air in a smaller diameter system. this dense heavy air will KILL the VELOCITY of the supposed high flow 3" exhaust system.

In order to take advantage of the phenomena that you are describing, there would have to be some trial and error done on primary lengths of BOTH the intake and exhaust. Equations will get you close, but doing it right REQUIRES some testing...
You can't just bolt on parts from summit OOTB




Everyone is so eager to tell me I'm wrong, but I don't see any evidence being presented

 

[joel5.0]

The air intake system and exhaust system work together, the exhaust system can only put out what the air intake system can pull in. they need to be sized in relation to each other.

Too big (diameter) exhaust systems can hurt power/torque if the intake system cant match the volume of air to keep the exhaust system flowing. Air, like gas is a fliud, it has fluid properties and will cool down(and contract) in an excessively large exhaust sytem. As the air cools, it will become dense and heavier, than hot air in a smaller diameter system. this dense heavy air will KILL the VELOCITY of the supposed high flow 3" exhaust system.

Backpressure is not the problem, you dont want excessive backpressure. but you do need enough pressure to keep the exhaust gasses flowing. too large exhaust will allow air to cool and become stagnant inside the system.

If you dont have an intake system that can keep your large diameter exhaust flowing at good velocity then its a waste and can hurt your numbers.

on top of all that putting a huge intake and exhaust system on a stock engine with poor flowing heads is an even bigger waste.

yes you proved a viper made an improvement with a 3" exhaust but put on a 4" or 5" and i bet it will be a dissapointment without other mods. so im pretty sure a 2.5" system will be enough for a 250-350hp v8.

sorry there are no proof in numbers here, but the physical explanation is enough for me to believe

Check the physical explanation highlighted above for a sec....... if the gases become stagnant inside the exhaust system, impeding flow, killing its momentum, cooled gases getting in the way of the exiting flow......... wouldn't it fall under the backpressure category? ...... Do you really think that's the case in a better flowing exhaust system?

A 4" or 5" ID exhaust system in a Viper?...... who mentioned such an alternative besides yourself? .....Velocity of the exhaust flow? ..... Do you know what happens to the velocity of the exhaust flow when it is restricted?..... doesn't it increase? Using your "too big" of an exhaust exaggeration example lets do it the other way, decrease the exhaust ID to 1.5"........ wouldn't the velocity of the exhaust increase? ..... simple Bernoulli's principle...... How would it perform now that the exhaust velocity was increased?

You are correct, "a 2.5" system will be enough for a 250-350hp v8".... but a 3" system, with a matching engine combination, will also be enough for a 250-350hp v8 that will out-accelerate the one with the 2.5" exhaust. It's not just peak HP ratings, it's also how fast that peak HP is reached. Reason why you see 600 RWHP setups getting beat at the track consistently by setups making 490 RWHP or less.

 

[vristang]

another way to phrase it...

restricted exhaust systems make it harder for the piston to push the gasses out the tailpipe

 

[cenok is family]

i have a belly button

 

[85_SS_302_Coupe]

Anybody else wanna quote screw me today? You guys are something else.

Also, that 3'' kit is on an 8 liter V10, not your little ~400hp 347. You can all say what you want, but i still don't see anyone showing me dyno proof of someone going to 3'' and picking up anything. What i know is that there hasn't been a production 500hp car that i know of that came stock with a 3'' exhaust (make that a true duel 3 inch exhaust...there are guys running 3'' in F bodies but that's because they have to run a Y pipe...big difference), and the engineers building these cars know a hell of a lot more than you bench racers out there know, so if 3'' is the key then why doesn't the GT500 have 3 inch, or why doesn't the ZR1 have 3 inch? etc etc.

 

[vristang]

Anybody else wanna quote screw me today? You guys are something else.

Why are you taking people questioning your theory as a personal attack?

Can't a couple of guys kick back and have a discussion



Well......
I guess I would like to 'quote screw' you again

Also, that 3'' kit is on an 8 liter V10, not your little ~400hp 347. You can all say what you want, but i still don't see anyone showing me dyno proof of someone going to 3'' and picking up anything.

Unbelievable,
You bring up an example (viper), and I show DATA proving advantages to 3" over production 2.5"
You still say I'm wrong
And now the Viper can't be compared to a 302/351w
If we couldn't compare them, then why bring it up?

Dispute the data if you like. But just continuing to ignore it doesn't help the discussion.

What i know is that there hasn't been a production 500hp car that i know of that came stock with a 3'' exhaust (make that a true duel 3 inch exhaust...there are guys running 3'' in F bodies but that's because they have to run a Y pipe...big difference), and the engineers building these cars know a hell of a lot more than you bench racers out there know, so if 3'' is the key then why doesn't the GT500 have 3 inch, or why doesn't the ZR1 have 3 inch? etc etc.

If these Engineers are the genius's (or is that genii ) you make them out to be, then how come the Viper picked up power when upgrading from 2.5" to 3.0"
(I'm not arguing these guys are dumb, just pointing out that they are stuck considering things we don't deal with...)

I know there is going to be data out there on the GT500 and ZR1 switching to 3" exhaust and gaining performance.
Heck, I found the Viper data on the first Google search


jason

 

[85_SS_302_Coupe]

For picking apart my posts you sure do miss the point.

The comment about the Viper is that STOCK is 2.5. I can understand 3'' being a step up on an 8 liter V10, but the fact still stands that the car came stock with 2.5 (unless i'm mistaken?) and still makes, what, 500hp+? Who has a stroker that breathes as much as a V10 and needs as much exhaust flow as a V10 that's N/A?

As for picking the posts apart, i don't have the time nor the interest to reply to each little comment...besides, you guys are sitting there playing the "prove it" game, when i still don't see any results aside from an 8 liter V10. Also, note that i said "N/A" in my original comment about this....even if the GT500 and ZR1 pick up anything, they're both blown engines and i'm willing to bet they're modded out when they get the 3'' exhaust. Boost is a whole different animal. Yet still, the engineers felt it was just fine with 2.5 inch.

You need to understand, i'm not saying no car ever needs 3'' exhaust, i'm just saying your run of the mill all motor 347 doesn't. Maybe if you're running it to 8k RPM but i highly doubt the original poster is running much past 6500, if that.

As someone else mentioned, exhaust velocity has a HUGE impact on this whole subject (which relates to my comment about too much carb, too much cam etc but nobody picked up on that i guess). If 3'' is great, then wouldn't 4 inch be better? Why not 5 inch? Why doesn't everyone just run 2'' primary, full length headers into 5 inch collectors with no exhaust? Because it's unnecessary, just like running a crazy 3'' exhaust on a bolt on 347.

Build me an 8-9K RPM race 347 with huge 2.20+ intake valves and a giant intake, and then i'd understand a 3'' exhaust. For a street/strip 347, it's a waste.

Now, proceed to pick that one apart

 

[89_LX]

Think logically about what you are saying here...
You are telling me that in order to increase airflow, you need to have resistance to airflow.
You are saying that airflow improves when airflow is restricted

not restriction, im saying you need a slightly PRESSURIZED system to keep the air flowing at a decent velocity to get it out of the system. If your saying that something slightly pressurized is heavily restricted then i call. if the exhaust gasses are moving quickly enough out of the system the piston will have no problem pushing the air out on the exhaust stroke. - which is what what this whole argument is about right

All im saying is that too big of an exhaust can hurt you unless you have huge power numners or are turning very high RPM

but according to your "the bigger the better" theory i should just go slap a 3" system on my 1.5 liter honda thats pushing 90hp--right?

[/QUOTE]

Check the physical explanation highlighted above for a sec....... if the gases become stagnant inside the exhaust system, impeding flow, killing its momentum, cooled gases getting in the way of the exiting flow......... wouldn't it fall under the backpressure category? ...... Do you really think that's the case in a better flowing exhaust system?

EXACTLY, you just claimed with that statement that too big of an exhaust can cause backpressure in the exhaust system. There is extra space for the air to take up in an excessiely large diameter system, when you dont have the power or arent turning enough rpm to move this air efficiently it cools down, becomes dense and heavy and becomes backpressure.

If you would have read my post above you would have read the part where i said you dont want EXCESSIVE backpressure in your system. But you need just enough pressure to keep the the gasses flowing through the system.

 

[95Vert]

This is interesting. Why don't engineers do this, why don't engineers do that.... Well if you're picking at the exhaust, why don't they come out with most of the mods we do when we first get a car like better induction, better exhaust, steeper gears, etc?? They have different guidelines/laws that they have to follow in order to be able to sell their product, not to mention the huge money they make out aftermarket parts. That was/is a week arguement. How can you say that they don't NEED a bigger exhaust, when you're not even sure if they come with what size exhaust. My buddy with a 07 Z06 stepped to a 1 7/8" with 3" exhaust along with a tune and a better induction system and it made close about 550 hp/tq, before the cam. Now, I could care less about the damn dyno numbers, I've learned to stop being ignorant, so that data doesn't mean much to me anymore, but we'll find out when we go to the track.

FYI, I'm getting a 1 3/4" with 3" exhaust on my puny 302ci, we can compare times once I get it running and we'll see if it helps or not.

 

[95Vert]

double post

 

[vristang]

I have better things to do than argue with you guys...
1. the mods here have proven that they will lock threads even if a civil debate is still progressing, just because someone whined
I would go off the deep end if I went 10 pages into a thread just to have it locked again.
2. You aren't listening to anything that Joel or myself are posting. You have been shown data based on your own example, then you you minimized it's importance with... 'well that's a v10, not a v8'
3. You are not taking the time to respond properly to questions posed, and you are being critical of the way I pull your quotes to make my points. I quote you so that we can stay on the same page, but because you can't keep up with that, I am an A-hole...
4. The only examples you have provided have been discredited; the Viper by myself, and the GT500 & ZR1 by yourself when I threatened to find data contrary to your theory. I didn't even have to find the data before you started backpedaling.

After this post, I am done here.



The main mistake you guys are making is that you are confusing 'Backpressure' with 'Resonant Tuning'
Let me clarify...
Backpressure can come from anywhere in the system. Example: 1 7/8" headers, using a 2" catback. The headers flow plenty for the needs of a strong 347 (just picking something at random), but the 2" exhaust will still provide Backpressure.

This example is not Resonant Tuning... this example is restricting the exhaust, period.
You cannot create Backpressure and simply call it Resonant Tuning.

Now, a properly 'tuned' exhaust will take advantage of Resonant Tuning... but NOT be restrictive.
You guys have a good grasp on that concept, but you are confusing Backpressure with Resonant Tuning.


Restrictions in the exhaust (in the name of Backpressure) will only add to the resistance against the piston on the exhaust stoke. Increasing resistance on the piston during the exhaust stroke limits the engines ability to ACCELERATE.

An analogy...
In HS/college football we used to run sprints pulling a sled loaded with weights behind us.
Obviously, with the added drag associated with pulling the weighted sled, I was slower.
Remove the drag, and I could ACCELERATE faster!

Same thing in an engine...
Remove drag on the piston, and the engine will ACCELERATE faster.
Remove Backpressure on the piston, and the engine will ACCELERATE faster.

Resonant Tuning is not the same as Backpressure.


All of this completely disregards the importance of the collector, but I will leave you guys to ponder that one on your own
(here's a hint to get you started though... where does the Resonant Tuning occur? at the muffler, at the midpipe, or at the collector?)

Wish you guys luck,
jason

 

[joel5.0]

not restriction, im saying you need a slightly PRESSURIZED system to keep the air flowing at a decent velocity to get it out of the system. If your saying that something slightly pressurized is heavily restricted then i call. if the exhaust gasses are moving quickly enough out of the system the piston will have no problem pushing the air out on the exhaust stroke. - which is what what this whole argument is about right

All im saying is that too big of an exhaust can hurt you unless you have huge power numners or are turning very high RPM

but according to your "the bigger the better" theory i should just go slap a 3" system on my 1.5 liter honda thats pushing 90hp--right?

Do you know what a "PRESSURIZED" exhaust system means?..... here's a thought, I do check for "backpressured" systems when they fail emissions testing every month...... do you know what is required to build pressure?........ the opposite to flow. Impede flow and what do you create?.... pressure. Simple physics. Now.... in a BALANCED system what do you do if you increase the exhaust?...... you have to match the intake to balance it...... or do you not? If you increase the exhaust and end up increasing the intake (more volume of air + fuel)..... won't you also increase the performance?...... since you also need the answers when academic questions are made.... the answer is YES!

EXACTLY, you just claimed with that statement that too big of an exhaust can cause backpressure in the exhaust system. There is extra space for the air to take up in an excessiely large diameter system, when you dont have the power or arent turning enough rpm to move this air efficiently it cools down, becomes dense and heavy and becomes backpressure.

If you would have read my post above you would have read the part where i said you dont want EXCESSIVE backpressure in your system. But you need just enough pressure to keep the the gasses flowing through the system.

..... I did not claim anything, since academic questions are out of your reach, based on your "logic", an open header situation will confront a mass of cooled gases molecules that will cause a backpressure situation in the exhaust....

Have you worked in VW beetles?....... you know, the rear boxer 4 cylinders engine types..... what would be the "ideal" exhaust ID, in a N/A setup to be able to make......... lets say, 11.5s in the 1320' ..... in a limited space of 16" be....... what about a turbo streetable boxer engine, running 10.8s in the 1320'...... 4 cylinders running a 3" exhaust.......or is a video required?

 

[vristang]

BTW,
You still have not supported your theory in any way...

Your theory being...
"The OP will run faster by removing the current 3.0" exhaust, and installing 2.5" exhaust"


Are you guys willing to reimburse the guy if his car runs slower with smaller exhaust?

 

[joel5.0]

For picking apart my posts you sure do miss the point.

The comment about the Viper is that STOCK is 2.5. I can understand 3'' being a step up on an 8 liter V10, but the fact still stands that the car came stock with 2.5 (unless i'm mistaken?) and still makes, what, 500hp+? Who has a stroker that breathes as much as a V10 and needs as much exhaust flow as a V10 that's N/A?

V10 engine, emissions compliant, insurable, noise acceptable, etc, etc...... that is a production car. Who has a stroker (not a production setup, better flowing, etc, etc) asa production unit?...... hint.......anybody that builds one. Here's a snapshot of a 550HP '66 Mustang with a 347 stroker........ yep, 3" full exhaust with 1 3/4" stepped to 1 7/8" custom headers.

As for picking the posts apart, i don't have the time nor the interest to reply to each little comment...besides, you guys are sitting there playing the "prove it" game, when i still don't see any results aside from an 8 liter V10. Also, note that i said "N/A" in my original comment about this....even if the GT500 and ZR1 pick up anything, they're both blown engines and i'm willing to bet they're modded out when they get the 3'' exhaust. Boost is a whole different animal. Yet still, the engineers felt it was just fine with 2.5 inch.

You need to understand, i'm not saying no car ever needs 3'' exhaust, i'm just saying your run of the mill all motor 347 doesn't. Maybe if you're running it to 8k RPM but i highly doubt the original poster is running much past 6500, if that.

Prove it game?..... does that mean yours is an unfounded opinion with no PROOF? 347 running to 8k RPM?.......

As someone else mentioned, exhaust velocity has a HUGE impact on this whole subject (which relates to my comment about too much carb, too much cam etc but nobody picked up on that i guess). If 3'' is great, then wouldn't 4 inch be better? Why not 5 inch? Why doesn't everyone just run 2'' primary, full length headers into 5 inch collectors with no exhaust? Because it's unnecessary, just like running a crazy 3'' exhaust on a bolt on 347.

Build me an 8-9K RPM race 347 with huge 2.20+ intake valves and a giant intake, and then i'd understand a 3'' exhaust. For a street/strip 347, it's a waste.

Now, proceed to pick that one apart

You really need to get some more experience.... I guess a 289 with an 850 cfm DP Holley would be overcarbed.... or a 1.2L rotary with a 600 cfm DP would also be overcarbed....... why not a 1150 cfm for either?...... by the same token...... why not a 1.5" exhaust for a 408 stroker?........

BTW.... love that exhaust "velocity" concept..... once the engine has used the scavenging pulse.... is exhaust "velocity" that important?...... or don't you want that refuse out of the system ASAP? ..... totally different concepts BTW.

And here's a real life example of a <500HP setup with a 3" exhaust setup....

1990 Red LX, 306, 5.4" rods, 95MM Lightning MAF, 75MM-R TB, ported HolleyII, Neil Erickson ported Edelbrock heads, Jay Allen cam, BBK 1 3/4" longtubes 3" collector, 3" prochamber, Moates chip, 3.73's, Mach1 disks (daily driver) 358RWHP/346RWTQ
18/29.2MPG

 

[85_SS_302_Coupe]

Ok...i give up. You guys are all right i guess. They told me my car would never run 12s with my combo, what do i know? It should go 12.20s with slicks. Maybe i should switch to 3'' and i'll dip into the 11s?

By the way, is the original poster making 550rwhp? I'm betting not.

So since everyone knows so much about exhaust, at what point is it necessary to get 3''? Should i have it now? Am i robbing myself power because i'm running 2.5?


By the way, here's my "proof" that 3'' isn't necessary. My buddy's '88 GT (fordfan if you wanna PM him), 347 with all the goods, tuned conservative for a break in. 2.5 inch full exhaust all the way out, with 1 5/8 full length headers, 385rwhp, should make an easy 400rwhp once it's broken in and retuned. I guess you'd all say he'd make 450rwhp with 3'' right?


View attachment 295383

Here's the dyno graph:
385HP Dyno on Flickr - Photo Sharing!

 

[85ragtop]

Keep this nice.

 

[lang williams]

I'd try a pair of 3" flowmaster 50 series. 3 chamber to quiet the inside of the car. also ditching the dumps an getting a set of tail pipes may quiet the inside of the car down. 3" 50's are 100 bucks each at summit.

 

[joel5.0]

Ok...i give up. You guys are all right i guess. They told me my car would never run 12s with my combo, what do i know? It should go 12.20s with slicks. Maybe i should switch to 3'' and i'll dip into the 11s?

Good for you....... nobody has said (at least I know I haven't) that YOU need to switch to a 3" exhaust system in order to improve your performance. However, could you set a better combo (not just one component) that could benefit from a better flowing exhaust setup?....... yep. Example?....358RWHP/346RWTQ + 18/29.2MPG + 8.2 @85.5 MPH in the 1/8th. and ~3550 weight.

By the way, is the original poster making 550rwhp? I'm betting not.

Not that I know, but he already has the system installed. OK.... using your same line of thought shown below......

And you're retarded if you think mufflers make power. An engine makes X amount of power and then the mufflers take away X amount of power. Getting aftermarket mufflers only reduces the loss.

Wouldn't you be more retarded (using your own words BTW) if you think that limiting the exhaust flow by suggesting the OP to downgrade from the 3", will increase power? If "aftermarket mufflers reduce the loss", wouldn't the "reduction" caused by a better flowing exhaust system (3") be less or none? ... and he doesn't have to spend a dime redoing the whole system, a simple (less expensive) mufflers replacement and the addition of tail pipes should be enough to quiet it down, as already suggested.

So since everyone knows so much about exhaust, at what point is it necessary to get 3''? Should i have it now? Am i robbing myself power because i'm running 2.5?

In your case.... nope. No need to spend money expecting a "snake oil" solution.

By the way, here's my "proof" that 3'' isn't necessary. My buddy's '88 GT (fordfan if you wanna PM him), 347 with all the goods, tuned conservative for a break in. 2.5 inch full exhaust all the way out, with 1 5/8 full length headers, 385rwhp, should make an easy 400rwhp once it's broken in and retuned. I guess you'd all say he'd make 450rwhp with 3'' right?

And that's fine..... a performing car is a COMBINATION of parts set to work together, since you are too focused on the exhaust ID...... that's a good combo with a 2.5" exhaust setup.


PS: And regarding......

This is like the people who think running without mufflers makes more power

When you're able to make $40 x3 in 8.4 seconds x3, in a 1/8th mile 5-3 grudge match back in 1979 (the equivalent to a full week pay in a part time job then)....... YES, running with open headers and the 850 cfm carburetor set, on a 294 CID Ford combo...... DOES make more power.... BTSTDT x2 (the others were for fun).

 

[85_SS_302_Coupe]

And that's fine..... a performing car is a COMBINATION of parts set to work together, since you are too focused on the exhaust ID...... that's a good combo with a 2.5" exhaust setup.

This only backs up everything i've said in this thread. Like i said, for quoting the hell out of every post i make, you guys have completely missed the point i'm trying to make and this thread is so far off base that it's useless to the original poster now.

As i said before, i just don't think HIS car needs 3'' exhaust. But, i'm by no means as expert, nor is anyone else in this thread so my advice from here out is to take it to a shop with a dyno and talk with the pros since this thread is going nowhere. Besides, aside from it being a 347 with Mac headers and 3'' exhaust, none of us know anything else about the guy's combo like heads/cam/intake/RPM range so i don't think anyone can really make the right call, and i don't think assuming a 3'' is right for it just because some other combo worked well with it.

Personally, i just can't get my mind off all the production 500+hp cars that are doing just fine with 2.5 inch exhaust systems. Saying that they might make more power with a 3'' system or with open headers is a moot point...the fact still stands that they're making more power than this guy is likely going to make and they're doing it with a full 2.5 inch emissions passing exhaust. Why can't he?

 

[vristang]

I thought I was getting frustrated constantly responding to this thread.
Turns out I am getting more frustrated reading all the double talk from this joker....

I will break your post into pieces so I can respond to it.
If you have a problem with that, then it's YOUR problem. Grow up and get over it. You whine more than a teenage girl...

i'm trying to make and this thread is so far off base that it's useless to the original poster now.

As i said before, i just don't think HIS car needs 3'' exhaust.

1. Yes this thread is off base for the OP. The OP needs to know if he will GAIN performance by removing his 3" exhaust and installing 2.5".
Can you provide ANY data that suggests the OP will gain performance with 2.5" over the current 3.0"?
Can you tell the OP that the performance gain from buying an entire NEW exhaust system, will be worth the money?
How much power will the OP gain with the smaller exhaust?

Answer these questions in your next post, or don't bother responding at all!!!

2. I highlighted the word "THINK" for a reason. That is your opinion, and you have NOTHING to back it up. You are advising the OP spend a big wad of cash on a smaller exhaust system because it will make his car faster. You have NO basis on which to make that assertion.

But, i'm by no means as expert, nor is anyone else in this thread so my advice from here out is to take it to a shop with a dyno and talk with the pros since this thread is going nowhere.

I agree...
Data should be what guides us, not some rhetorical internet BS.
You were tasked with providing data to back up the 'common knowledge' that Backpressure was required for best performance.
You haven't providing anything significant. Every example that you bring up, you then say is irrelevant.

If the need for Backpressure was common knowledge, then there should be large quantities of data out there to support that conclusion.
Where is it?

Bring DATA in your next post, or don't bother posting at all!!!

... and i don't think assuming a 3'' is right for it just because some other combo worked well with it.

So, the fact that another car did well with 3" exhaust is irrelevant.
But when you bring an example of a 2.5" exhaust performing well, then it's a good data point?
You are so full of BS

Stop double talking in your next post, or don't bother posting at all!!!

Personally, i just can't get my mind off all the production 500+hp cars that are doing just fine with 2.5 inch exhaust systems. Saying that they might make more power with a 3'' system or with open headers is a moot point...

You keep bringing up production 500hp vehicles with 2.5" exhausts.
But when I bring DATA proving that there is a performance gain to be had in those cars with 3" exhaust...... Then you claim the data doesn't match up with the OP's car?

You are flip-flopping your story!
It's OK to talk about production cars with 2.5" exhaust, but the second an example of these cars gaining performance with 3" comes up you backpedal.

the fact still stands that they're making more power than this guy is likely going to make and they're doing it with a full 2.5 inch emissions passing exhaust. Why can't he?

We've already PROVEN that these cars will make more power with 3" than the factory 2.5"
Why?
Because the 2.5" exhaust is restrictive compared to the 3"
In other words.... The factory exhaust provides Backpressure.


How about this....
You find some data of a 350hp car that gains power with 2.5" exhaust compared to 3"???
Just some data point that will support your theory.


You have been tasked with providing very specific forms of proof.
You have brought nothing but rhetorical nonsense.
Hell, on the first page of this thread, I asked you what books you were reading.
I still haven't gotten a response on that



Plain and simple answer for the OP...
Keep what you have.
No one here can prove that you will gain performance with SMALLER pipes because you won't.
Even if you did, would it really be enough gain to justify the cost of replacing the entire exhaust system?

Well, it's a simple fact? Haven't you guys ever read any books on this crap? I'm not talking magazines either.

You still haven't cited ANY sources.... that is bad form in a tech discussion...


Again, if its a "simple fact?"
Then there should be data everywhere

(I love the way your lame ass put a question mark in there )


jason