Put stock muffler back on, more Torque?

Philip · Apr 22, 2021

A year ago I had a shop remove my mid muffler on my 3.6L, I got tired of the sound to be honest, not a V8 lol. Anyway after having them put on the stock one today I instantly noticed an increase in Torque just giving the gas pedal a press. Is this due to back pressure added? I just like that my truck is super quiet now.

Hanover Fiste · Apr 23, 2021

Philip said:
Is this due to back pressure added?

Added back-pressure reduces HP & torque. A properly tuned exhaust system has the least amount of back-pressure. Some people confuse back-pressure with scavenging; they are not the same.

Philip · Apr 23, 2021

Well it definitely feels more powerful in 1st gear, weird lol.

tidefan1967 · Apr 23, 2021

In 99% of cases muffler swaps(and especially straight pipes) do nothing for performance. In my experience a complete aftermarket catback system with longtubes and tuning can provide some very noticeable performance gains but can be pretty damn expensive. Most muffler shop exhaust work turns out to be junk that's not mandrel bent and either rusts out or falls apart way too fast. Personally I wouldn't bother on a NA V-6 unless you plan on adding other power adders later on.

pacofortacos · Apr 23, 2021

I have seen the same change with the hemi playing with the exhaust. It may change a bit more as the computer adapts.
I have confirmed changes just swapping from the muffler back on the same day using hills with cruise control engaged - the more restrictive exhaust seemed to delay the kick down into a lower gear to get up the hill and in some cases not down shift at all.

crazykid1994 · Apr 23, 2021

Swapped my stock muffler in the hemi to the carven and my truck wouldn’t hold eco at 50. Eventually swapped to a Borla catback and now it’ll hold eco even with my 35s at 65mph.

corneileous · Apr 23, 2021

crazykid1994 said:
Swapped my stock muffler in the hemi to the carven and my truck wouldn’t hold eco at 50. Eventually swapped to a Borla catback and now it’ll hold eco even with my 35s at 65mph.

View attachment 245241

Which carven did you have? I’ve had my Progressive on so long now that who knows, maybe my motor was still getting broke in but it feels peppy enough to me. ‘Course then again, I’m not running big ole heavy 10-ply 35’s either, even with my 3.92 diffs. As far as whatever my Eco light does, that was only enabled for a short time after I bought it and then quickly turned it off.

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crazykid1994 · Apr 23, 2021

corneileous said:
Which carven did you have? I’ve had my Progressive on so long now that who knows, maybe my motor was still getting broke in but it feels peppy enough to me. ‘Course then again, I’m not running big ole heavy 10-ply 35’s either, even with my 3.92 diffs. As far as whatever my Eco light does, that was only enabled for a short time after I bought it and then quickly turned it off.

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I left the eco light on just for kicks. Mds is disabled. I had carven progressive. I think part of it is just how the engine tuning is. Carven progressive was on from 12,000 miles to around 20,000 miles. I got tired of it and wanted something new and quieter for when I do headers

novelmike · Apr 23, 2021

My truck definitely seems more peppy since I removed the Carven and installed a Walker Quiet Flow muffler.

Hemi395 · Apr 23, 2021

I have a Mufflex 24 on my truck since about 6 months after I bought the truck. Its got 72k on it now and the Mufflex is starting to rust pretty bad being in New England. I still have the factory muffler that is basically brand new, might just slap that back on after reading this thread...

Hemi395 · Apr 23, 2021

novelmike said:
My truck definitely seems more peppy since I removed the Carven and installed a Walker Quiet Flow muffler.

Is that an aftermarket version of the factory muffler?

novelmike · Apr 23, 2021

Hemi395 said:
Is that an aftermarket version of the factory muffler?

My best guess is yes it is.

I’m not sure if it sounds any different than a stock muffler. I’ve had a Carven on for so long I do not remember what the stock exhaust sounded like.

GsRAM · Apr 24, 2021

In most cases changing the exhaust without any other changes to the engine seldom yields any noticeable power increase.

They sound good and I'm all for that, but in most cases perceived power increases are placebo effect.

I enjoy my mustang's loud exhaust, but its not my DD. When I was in my teens and 20s I wanted a loud exhaust on anything I owned. Now that I'm older when I'm towing my TT, the last thing I want to hear is a loud exhaust the entire trip.

But to each their own of course. Everyone is different.

I still appreciate hearing a loud exhaust on a V8 powered vehicle. Music to my ears and always will be.

lazer · Apr 26, 2021

I know in some older engines like the FE390 it need back pressure for low end torque.

chris52010trx4 · Apr 27, 2021

Hemi395 said:
I have a Mufflex 24 on my truck since about 6 months after I bought the truck. Its got 72k on it now and the Mufflex is starting to rust pretty bad being in New England. I still have the factory muffler that is basically brand new, might just slap that back on after reading this thread...

Just went through this 2 weeks ago.

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Cableman · Apr 27, 2021

Im gonna get that k&n muffler, 304ss and not much louder then stock but straight through design. $399 isnt too bad and should last forever!

Hemi395 · Apr 27, 2021

Cableman said:
Im gonna get that k&n muffler, 304ss and not much louder then stock but straight through design. $399 isnt too bad and should last forever!

Just looked at that, I think thats going to be my next muffler as well. That will outlast the truck!

csuder99 · Apr 28, 2021

The exhaust systems on modern vehicles are tuned pretty well from the factory and replacing random parts generally does not make it overall better. It might gain a few HP at the top end and sound better but it typically comes at the cost of drivability.

I remember decades ago a car magazine tested aftermarket exhaust systems for a 2.0l 16V hot hatch. Dyno, 0-60, top speed, noise. Only one system was deemed to be better overall, coincidentally it was made by the aftermarket brand of the OEM manufacturer. Having been involved in the development of the car they had the necessary know-how and experience to make a well-rounded product.

Philip · Apr 28, 2021

It's actually funny though, because I put on the stock muffler which is around 40-50lbs easily, yet when I stomp the gas from a stop the tires light up. Without the muffler, barely any tire slip. I'd call that a low-end torque increase.

Put stock muffler back on, more Torque?

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