No mufflers at all

[SmockDoiley]

I've been on here for a number of years now, and I've never seen anyone talking about just deleting the muffs all together. I work at Midas and I have seen it done many a time on pickups so why not a car like a mustang.
So then comes this customer and we hit it off because we were both in the Marine Corps. I've since become his mechanic of choice now and we both have SN-95 5.0s. He suffered from the same problem as myself, aftermarket mufflers but no sound. Since I work at a shop I can't recommend removing the cats; plus I dont believe in destroying the environment. First thing I noticed were the rust holes in 2 year old flowmasters which is the second time I've seen that occur. IMHO I dont recommend flows because of that.
Anyways, I told him I could remove the bad flowmasters and straight pipe it for $40, and he goes for it. Long story short, it cured his problem and it sounds great. There is no drone at highway cruise, its not overbearing at idle or in the cabin, but when you hit it, it barks! I'm sure it may be cackley for the guy behind you, but I dont care about him anyways. He was very happy, and I liked how it sounded so much that I did it to mine today. Its just using the 4 cats to quiet the exhaust down, and I like how it sounds. Its similar to like an old Impala with glasspacks if you know what I'm talking about.
The other great thing is the cost. Where else can you get a good throaty exhaust sound and pick up some horsepower for $40?? So if you want sound and cant afford a couple hundred bucks or more, than just eliminate the mufflers. And in case you are wondering, it is totally legal. Its really the only way to get loud unless you get an O/R pipe which costs even more money.

 

[Foxfan88]

i got a bud who runs straight pipe in his 351M truck, its alright, sounds ok, i ran straight pipe for a week ( was getting new exhaust parts and didnt have em on yet) and it sounded like total ass! i loved how it SCREAMED at WOT but was LOUD! in regular driving it popped and crackled like a mother.

i got some race bullets which is a straight thru muffler so it will be super loud and give the advantage of running straight pipe!

mustangs need a muffler for some reason. i just go with it.

 

[cenok is family]

deleting your mufflers causes a big loss in back pressure which results in loss torque.

no mufflers = slower car

 

[86bluecobra]

i agree about the lose in back pressure. also most of us guys i dare say have rmoved our cats so straight pipes is just not an option unless we want noise violation tickets.

 

[BaXTeR3221]

Yea i agree, on both of my 5.0 cars and everyone else's i know of, the cats were gone so not having mufflers wasn't feasible. Also, without the back pressure, i don't know how the car would run. There are a lot of straight through mufflers, i would suggest those if thats the sound you want.

 

[mustangjoe87]

5.0's sound like ass without mufflers and cats.

 

[Mustang5L5]

You lose a lot of torque if you run without cats and mufflers. I had a friend who deleted his cats and mufflers on his 5.0 and went from running 14.8 @ 93MPH to 15.1's @ 91MPH. We popped some mufflers back on and he picked up the lost power.

Honestly, no mufflers only sounds great at WOT or when you rev it free. When you load it up like slipping out the clutch or bogging down or chugging along in a higher gears is sounds like ass in my opinion.


PS. i have flowmaster cat-backs on both my cars and live in New England. One is 4 years old the other is 2 years old and both are still rust-free. Here's a shot of my 4-year old cat-back

 

[4G-KDMP]

deleting your mufflers causes a big loss in back pressure which results in loss torque.

no mufflers = slower car

that is the same thing i've heard 100 tmes

 

[2000xp8]

I agree, flowmaster quality is crap, not much if any better than mac. And i run a flowmaster catback. I've had 2 catback rust out, got the third for free, so....

I've also heard the no mufflers sound on a 5.0, with and without cats, boths ways sounded like crap.

 

[SmockDoiley]

I never said run without cats or mufflers. You need at least one of them, and personally, running without cats is stupid but whatever floats your boat.

 

[larrendeuce]

I'm not going to pretend to know everything about exhaust and physics but I picked up a few things during my research. Backpressure is bad, no backpressure is good. What many consider adding backpressure is good for power incorrect. Having pipes in too great of diameter causes a loss in velocity. That is what causes cool down of the exhaust gases and a loss in power. Performance mufflers aside from various increased flow rates also prevent pressure wave reversion which cancels out the scavenging effect.

This is why 3" exhaust on a stock engine hurts power, and why no mufflers causes loss in low end power.

 

[feifong]

Heres what i have ran, Stock manifolds ,88hpipe with cats to dual flowmasters no sound at all.,,, Stock manifolds ,88hpipe with cats to dual spintechs sounded the same as flowmasters with more interior noise. I then ran BBK lt's by themselves no muffs no nothing.. Way too loud for normal driving. Now i run BBK lt's O/r bbk Xpipe. to dual flowmasters. Sounds Exactly like it was with ONly BBKLT's BUt quieter wich i like a lot. I get the sound of LT's But quieter. I heard an 88 with just straight thru no muffs stock manifolds sounded way too raspy. This was on my 83 vert.

 

[Foxfan88]

i've always heard that backpressure is NOT GOOD. I dont see why it would be good at all, hindering the flow of exhuast doesnt help at all.

you want a free flowing exhaust that will help scavenge the rest, this is what the collector is for. as one exhaust pulse travels past it, it helps pull the gas from other cyls.

i am not some big science guy on exhaust but thats what i have read, and makes more sense than having backpressure.

the stock exhaust is finetuned FOR THE STOCK car, the stock pipe size and setup lets the air gain MORE speed, which means a faster cycle or burning the gas and gett it out ASAP which means more torque.... which is why it runs better with it. You start changing it with a basically stock engine. then you may notice torque loss, bc it cant gain velocity it could in a bigger tube. I have a book on stangs exhaust and it goes in depth on setups, lots of formulas to determine proper primary dia. , proper exhaust tube length, dia. and where to place the crossover tube.

sure the basic exhaust mods may hurt low end torque feel, but it should gain a bit in the higher end HP, where it revs higher making more exhuast to fill the tubes and achieve more velocity.

according to what i have read, that makes more sense, is you dont want backpressure, or the biggest tube possible, you want the proper size tube, which may be hard to get and you would have to custom make your exhaust, but the aftermarket comes close. every application is different, they cant optimize everyones performance. but can come close i would say.

you dont see topfuel having backpressure, they have SHORT and HUGE tubes, to get the exhaust OUT ASAP, they burn so much fuel and air and need it out asap. but they still makes thousands of lb/ft of torque. the burn more fuel than you can imagine, imagine our engine, with little mist spurts of fuel. well a top fuel have the equivalent of 4 kitchen faucets running at the same time. thats alot of fuel lol

same for use, we want to exhaust out asap, but if you throw a big tube on it wont help air will be lazy moving and bouncing around inside. so you need the proper tube to make it gain velocity.


here is the article i read....

-----------It may seem intuitive that bigger, more open exhaust would be the best for engine performance. Some believe that there is a proper amount of exhaust back-pressure for optimum performance. Both of these theories are wrong. There are a few key things that make exhaust flow different than other fluid flows. First of all, the exhaust is coming out in pulses. When each cylinder exhausts, a large surge of flow enters the exhaust system. Then it stops again until the next exhaust stroke. True, larger exhaust ports and tubes will flow better but flow is not the only thing to consider here. If you size the exhaust tubing properly, you can take advantage of the inertia of the exhaust pulses similar to what can be done on the intake side. When the cylinder exhausts, the pulse builds a pressure in the exhaust tube. Once the valve closes, this exhaust pulse is traveling down the tube with velocity. Because of this, a slight vacuum is created at the valve. This pressure-then-vacuum pulse will travel all the way through the exhaust system assuming the restriction is low and the tube diameter does not change much.

The tubes for each cylinder to the collector are called primary tubes. These primary tubes can be sized, both diameter and length, to optimize the exhaust inertia while keeping minimum restriction. It is a trade-off and will only be optimum at a specific RPM and load. This is very similar to optimizing the intake system and the same key things apply. For low RPM performance, a small diameter, long tube will give the best port velocity, and exhaust inertia. For midrange performance, a shorter length, larger diameter runner is best. For very high RPM, a very short, large runner is needed because restriction is the biggest problem at high RPM.

By grouping primary exhaust tubes into a collector, the vacuum pulse from one cylinder can be used to create a vacuum on the other exhaust ports. This vacuum will cause the exhaust to begin flowing more quickly as the exhaust valve opens. The collector must be long enough and small enough to keep the inertia of the exhaust pulse optimized while keeping back-pressure low.

Back-pressure is something we are stuck with, not something we want. By optimizing the inertia affect, some back-pressure will be realized during the peak of the exhaust pressure pulse. It is not something you want but rather simple physics.

Once you get past the end of the collector, you want to release the exhaust with as little restriction as possible. The end of the exhaust header is not really the end of the collector. The collector area in the exhaust should usually be about 18" to 24". If you have 2 banks of cylinders with each bank having it’s own collector, you will also have alternating pulses from each bank. In order to reduce restriction, you should place a tube between the banks at the end of the collector area. This will allow pressure pulses to swap back and forth which will even them out and allow smoother flow through the rest of the exhaust system.

At very high RPM, the restriction becomes a much bigger problem. Because of this, attempts to utilize exhaust inertia are generally abandoned in favor of reducing restriction.---------

 

[86bluecobra]

wow i guess you guys have done some research. i donot agree 100% with what you guys are saying though. The terminator cobra's actually lose power with a 3 inch exhaust over the current 2.5 they come with. why you may ask. well according to mmff mag because of the lose of back pressure. super charged applications need some back pressure.

 

[Foxfan88]

wow i guess you guys have done some research. i donot agree 100% with what you guys are saying though. The terminator cobra's actually lose power with a 3 inch exhaust over the current 2.5 they come with. why you may ask. well according to mmff mag because of the lose of back pressure. super charged applications need some back pressure.

i am sure SVT fine tuned the exhaust for it, for more power, the cobras are pretty high performance as is, i would be content with a 390 horse mustang from the factory lol

 

[SmockDoiley]

Sorry I havent taken video yet, but I drove it around tonight and I really like it. I guess I was just getting pissed when everyone was talking about running no cat or no muffler and having it sound like ass. Its like puting words in my mouth. Its pretty obvious you wouldnt want to run a straight through system on the street, and I never said you should. I basically have a factory 5.0 that is a my daily driver and I wanted some sound, but I dont feel like dumping hundreds of dollars into my exhaust so I got some mandrel 2.5 cat back pipes from Advance Auto for $40, and then built pipe where the muffs should have gone.
I dont know what you people are talking about being unbearable at idle or cruising. I still cant hear it idling, and there is no drone in the car when driving. The only time I hear the exhaust is if I'm outside of the car or when I'm flooring it. In any case, it sounds just as tough as an o/r pipe and aftermarket mufflers but way cheaper. I also dont believe in running an O/R pipe on the street. Its not only illegal but bad for the environment. So if you want sound, want to stay legal and care about breathing then the only thing you can do is ditch the mufflers.
As for backpressure, I have the factory 2.25 4-cat H-pipe going into mandrel 2.5 straight thru catback with 3 inch tips. So if you all are running no cat X-pipes with aftermarket mufflers in a true 2.5 inch exhaust you may actually have less backpressure than me so why are you bagging on me about losing my mufflers. And for the people using the bullet mufflers, your not getting any backpressure from those either.
Besides, I have a big block 85 fox, so do you think I care if I lose some torque in my 95 daily driver. There isnt a single thing I can do to this thing to make it as fast as my 85 so why do I care about crunching numbers and getting technical about exhaust gas scavenging. I simply wanted to offer a solution to getting sound from your car for next to nothing in cost because unless you lose the cats which I dont recommend, aftermarket mufflers are a waste of time.
Now if you want to talk about a badass sound, try a 2.5 inch offroad X-pipe with MAC dumps on a 466 with a 230/230 duration cam. And before you complain about me not having cats on that, I drive it like 200-500 miles a year.

 

[fidstang]

Back pressure= bad, loss of power
restrictive= not so bad, loss of power, gain of torque

There's always a trade off and a very fine line.

 

[mob]

Now if you want to talk about a badass sound, try a 2.5 inch offroad X-pipe with MAC dumps on a 466 with a 230/230 duration cam. And before you complain about me not having cats on that, I drive it like 200-500 miles a year.

Put any muffler on a 466 and it will sound badass..

I honestly could care less about backpressure, I have an O/R hpipe with bullet mufflers that just cut off there with not tailpipes. It pulls just as hard if not harder then it did with my flowmasters and tailpipes. Ive tried running open pipes (just unbolting the catback) and it wasent too loud but it just sounded like COMPLETE ass, no other way to put it, wot and idle sounded nice, but once you touch the gas, it has an old dump truck sound and gets old VERY fast. Bullet mufflers are just as loud and sound 100 times better, raspy, better tone, and race car sound up top. Oh and I didnt spend hundreds of bucks on my setup, 77 for the mufflers, and 60 to have them installed.

My theory on it is, like what was said before, the more velocity the system has the more torque it will have. You dont need a muffler for that, just longer pipe, size of piping will depend on how much power you have and much it can flow.

 

[25thmustang]

I never said run without cats or mufflers. You need at least one of them, and personally, running without cats is stupid but whatever floats your boat.

Running without cats is stupid... Oops had them on for a while last summer, but otherwise dont run cats on mine.

As far as Flowmaster quality, I didnt have an issue the few years I had mine. And have a Mac one now. It was great (im talking 6 years maybe more) but this past winter took its toll. The tips are rusted (not too bad, but still) and havent looked at the mufflers or pipes yet.

This whole back pressure, torque thing... None of us are looking for every ounce out of our cars. If you did, you wouldnt be doing so by mufflers or custom exhaust. So I say screw the whole back pressure, scavenging debate, buy what you like, and run what you brung.