After enjoying a few years with the sweet sounds of a GMMG cat-back and stock exhaust manifolds, the need for more power prompted me to get headers. After they were on the car it was much louder, even with a catted y-pipe. I was ok with it for a while, but a few long trips later it began wear on me. I had to make a change to something quieter, but still maintain the good flow of the GMMG.

Here's what I wanted out of my new exhaust system:

* Flow enough for 700 rwhp with FI
* Must go over the axle
* Want some sound at WOT, but mellow at idle and cruise
* No rasp from 2000-2300, or anywhere else

My options were:

* Bassani 2 1/2” true dual cat-back
* SW 3 1/2“ dual exit cat-back
* Mufflex 4” dual exit cat-back
* Mufflex 4” single exit cat-back (w/Magnaflow)
* Custom 3” true dual system

Found this yesterday and reordered it based on power potential: (quoting JRP)

* 2.75” single system - 310hp engine
* 3” single system - 370hp engine
* 2.25” dual system - 457hp engine
* 3.5” single system - 503hp engine
* 2.5” dual system - 513hp engine
* 4” single system - 657hp engine
* 3” dual system - 812hp engine

After much deliberation, I decided to go with the Mufflex 4-inch single exit with Magnaflow muffler. My exhaust guy, Rich in Wylie, TX did an excellent job installing this system along with a Kooks 2x3” into 4” catted y-pipe. Fitment is fairly tight with this system, so finding a muffler shop that will do the extra tweaks to make it hang right is very important.

Mufflex impressions... The dreaded rasp is gone. It’s now quieter than the GMMG at idle and cruise, but still has a good bark at WOT. The tonality is overall deeper. Hitting the gas while going under an overpass sounds like a stout muscle car again instead of an old truck with a rusted out muffler. Don’t get me wrong, I love the way a GMMG sounds, but just not with headers.

EDIT: Added pics after I got the entire system ceramic coated black. This was done locally and cost about $325. I think it might actually be a little quieter now, but it's hard to tell because the car's been down for 2 weeks.

 

Good info, glad you found a set up u dig. I personally like to be obnoxiously loud...nothing screams im important like standing up and screaming im important

 

I would have tried adding something in the I pipe before buying an entire new exhaust system.

 

i hate the way the gmmg sounds. i feel if you want your vehicle to sound like that, save yourself the money and just take a hammer to some 3" pipe and leave the mufflers off. there is your chambered exhaust. i never understood why someone would want such a beautiful car to sound like my 84 chevy truck with duals and glasspacks.

 

I love my GMMG! I have hooker long tubes and hooker ory and I have got more compliments on my exhaust setup then I can count.

 

I havent heard the gmmg on a fbody at all, but i do know the mufflex is awesome. Has great tone, no rasp, and like mentioned above is quiet enough when you want it to be, and loud enough when you want it to be.

 

Another reason was that my wife wouldn't ride in the car any more because she thought it was too loud. It was cheaper for me to get a new exhaust.

To all those out there with GMMG - I'm not bashing! It's a bad *** sounding system that flows really well. The Mufflex sounds pretty good too with plenty of volume, but is not as aggressive as the GMMG. Another bonus, is now I can actually hear my supercharger!

More opinions welcome!

 

What did you do with your old gmmg?

 

Put it on the wife's mini-van!!

 

Post up some pics and a sound clip! Sounds like a great setup.

 

Ditto & Ditto!

 

Mufflex is awesome, I want to go with that same magnaflow muffler setup on my car.

 

sounds like a decision that you will be happy with, good luck!

 

Agreed. I want to hear it.

 

His car or his wife's mini van?

 

His car. I have gmmg, I know how it sounds. Mine will be for sale shortly.

 

http://www.thirdgen.org/techboard/ex...ml#post3712408

I just had a 4inch mufflex installed on my 3rd gen. Whats the part number for the magnaflow muff? Thanks.

 

They don't list the part number on the invoice, but it's probably #14153. It has a 4" in/out and a 14" L x 8" W case. The muffler specs says it has a 20" overall length so they probably cut off the 3" of pipe of both ends and welded the bends right too it.

 

Glad your new set-up worked well for you. I also didn't like how my GMMG sounded with LT's & ORY. It took a lot of tweaking to get mine to sound good again - cats, a powerpack in the I, and Hooker resonator tips. Got rid of all the rasp.

 

Thread is not so worthless now.