Performance Loss With Loudmouth?

If you want to sound good DON'T run straight pipe or lm1's!

Magnapacks will do the job. Mufflers dont affect power output. Get something that sounds decent.

v8's don't really sound ricey. You can go on youtube and search different exhaust combos. If you want LOUD you will have to change your mid pipe to off road X or H depending on emission testing in your state. A catback will give you some tone and make it a tad louder. Search for Flowmaster, Mac, Borla, Slp lm2, bassani just to name a few.....

hawkfish78 said:

What would you recommend? I want it really loud, but I don't want to sound ricey.

Sent from my DROIDX using Tapatalk

Click to expand...

Magnaflow Magnapacks or Borla Stingers. I personally like the Stingers just a bit better.

Magnaflow Magnapacks Catback with Mac O/R H pipe - YouTube

2003 Mustang Gt Borla Stinger Bassani O/R X - YouTube

Not too loud at part throttle, but it gets REALLY loud when you get on it. What midpipe and headers will you be running?


Also, about the loss in low end torque. It is of my personal opinion that that is complete BS. I've heard it SO much on so many different forums, and I've never once seen any proof to back it up. My personal experience is a .2 second and nearly 2 mph gain in the 1/4 mile with an offroad midpipe and catback. And just because I'm bored right now, I'll go into a more in-depth explanation.

Back pressure, which is simply the force against the air flow created by catalytic converters, restrictive mufflers, bad bends in the pipe, etc., is ALWAYS a bad thing. Yes, your car requires a certain amount to do some complicated stuff inside the heads, but that amount is easily provided by the friction losses and aerodynamic drag created from simply moving the air from the front of the car to the rear via the exhaust pipes. The cats create quite a bit of back pressure, and removing the cats (and/or restrictive muffler) will decrease that pressure and create more power.

The problem most people have is separating back pressure from exhaust velocity. Faster moving air helps pull the exhaust gases out of the combustion chamber better (read: scavenging), which is the reason why long tube headers work. Your factory exhaust has a 2.25 inch diameter, from the exhaust manifolds back. If you replace that with a 3 inch exhaust, the speed of the air moving through those pipes is going to decrease (as per some relatively simply fluid dynamics principles), although not by a whole lot because the 2.25 inch piping itself isn't really restricting much in the first place. So, slower moving exhaust = less torque.

When you go and put an offroad midpipe and/or catback on your Mustang, you are both removing back pressure (by removing the cats, better flowing pipe bends, etc.) and decreasing the exhaust velocity (by increasing the diameter of the pipe). However, the amount of power/torque you gain by removing the back pressure is MUCH greater than the amount of torque you lose from the decreased exhaust velocities.

Make sense?

great explanation...one of my (many) pet peeves is people wanting "enough back pressure"

The reasoning is that a certain residual pressure in the exhaust helps prevent "leakage" of mixture from the chamber during the overlap period. The theory is valid: Witness cars with big cams that do lose low-end torque. Engines with aggressive cams have lumpy idles because they are, effectively, running like **** at low RPM and part of this is caused by mixture migrating out the exhaust during the long overlap period. It is also for this reason that big cams are not typically emissions-friendly...

Modern cars have such little overlap to begin with for emissions purposes that on a car with stock cams, you're not likely to see much -- if any -- loss in low RPM torque by reducing system backpressure.

If you've got cams a reduction in exhaust backpressure may affect the low RPM torque by exacerbating the mixture migration out the exhaust during overlap.

LM1's sound good as long as you have cats. A muffler delete would just sound like complete ass.

2004 mustang Gt - SLP catted X SLP lm 1 - YouTube

But as far as straight-through mufflers go (SLP, magnaflow, etc) Borla Stingers PWN

007 said:

Mufflers dont affect power output.

Click to expand...

I switched from Flowmasters to Magnaflows in one of my old cars, gained a tenth at the track.

Stumbaugh said:

I switched from Flowmasters to Magnaflows in one of my old cars, gained a tenth at the track.

Click to expand...

You just drove "a tenth" better....

i have a pair of lm1's coming in today and when i get them on i could let you know. many people dont like the sound of them, but from what i can tell on youtube its not to bad im looking forward to having them put on. i have flowmaster 40's yeah they were good from stock but the drone is terrible and they are only loud in higher rpms. Maybe with an o/r h it would sound better but im not going that route, with my luck id get introuble with the whole catless exhaust. I should have them on by wednesday

so i got my slp lm1's on today. let me tell you they sound a whole lot better than flowmaster 40's. they have a louder idle and sound a lot cleaner and smoother. i didnt feel any loss in power. when i get on the highway all i hear is drone with the flows and it was horrible with the slp's they have no drone at all they are quiet when cruising but when you get on the pedal they scream they are awesome. they have deep tone to them also not just loud. they are a good muffler if you have emissions strict state or you wanna get the cats on. they are a pain to install but they are worth it to me they sound so much better than the flows

Report back to us after a month or two of driving when the packing material in those mufflers has settled, stiffened/hardened etc. It'd be interesting to see if, over time, the character of the sound changes and if a drone appears.

hawkfish78 said:

Yeah I've been listening to exhausts on youtube for a couple months, but its hard to tell what they sound like in person. I can't change to an offroad h/x pipe because I live in Oregon which has pretty strict emissions tests and random cat checks. I was planning on doing the slp loudmouth 1s because I heard they were the loudest. After talking to a local exhaust shop they recommended flowmaster 40's how loud are those compared to the lm1's?

Sent from my DROIDX using Tapatalk

Click to expand...

Whereabouts in Oregon? If you want and are in the pdx area, pm me and I'll have you come to one of our mustang meets. You can hear the combo of bassani x(w/cats) and Borla CB (stinger).

It's loud as hell, and the best combo I think I've ever heard.

fiveohwblow said:

You can hear the combo of bassani x(w/cats) and Borla CB (stinger).

It's loud as hell, and the best combo I think I've ever heard.

Click to expand...

IMO, 4-valve 4.6 + catted x + Borla Stingers = the BEST sounding Mustang ever.

sneaky98gt said:

IMO, 4-valve 4.6 + catted x + Borla Stingers = the BEST sounding Mustang ever.

Click to expand...

Agreed, as per my post.

Offer stand for ya OP, you can hear it locally.

trinity_gt said:

Report back to us after a month or two of driving when the packing material in those mufflers has settled, stiffened/hardened etc. It'd be interesting to see if, over time, the character of the sound changes and if a drone appears.

Click to expand...

There is no packing in the LM1 catback.

I liked the sound of mine but wanted to go back to an o/r h and chambered muffler.