I just had the GMMG exhaust installed by a quality muffler shop(yeah they do exist) today. I have to say that reading all of the opinions on this board were very confusing to say the least. I was able to hear the exhaust on LS1sounds.com and from that I liked what I heard, so I took a chance and I came up big. I still have my factory manifolds and Y pipe with cats. When starting the car it barked to life. At idle it has a deep rumbling growl form the outside. From the inside of the cabin it is more audible than stock, but not uncomfortable in any way. From what some have claimed I thought it would be much louder. It is perfect. At low rpm's pulling away from a light is where the fun starts. From about 2000-3500 rpm's this exhaust lets you know you are not in Kansas anymore Toto. It has a deep growl that sounds so menacing. As rpm's rise above 3500 the decibels level out and the sound seems to take to the background as you come up to highway speed normally without WOT. Once at cruising speed I can tell you there is not one bit of drone. The drone factor was my biggest concern. None!!! Now for the good part. When coming from a light or entering a highway on ramp and going WOT all I can say is Holy ****!!!! Words really do not do justice to the sound this exhaust makes. It sounds throaty with no rasp at all. It screams like I hoped it would. I know this is a pricey exhaust compared to others. I also want to say that it actually was a direct bolt on exhaust. The dude at the muffler shop said he never saw an aftermarket exhaust fit right on without having to cut or weld something. After becoming an owner of this exhaust I would highly recommend it. I am intending to add KOOKS LT's with their catted Y. I know this will add some decibels but from where it is now it will not be to big a leap.
Here are some pics of the event. Iwould post a movie but I am having trouble doing that.


The last view of the old exhaust.


The IM pipe being fit into place


The star of the show


Finishing up

 

Nice man...glad you like it. You'll LOVE it with headers and cats.

 

I'm jealous!

 

Never knew GMMG looked like that. Sweet!

 

Cant Wait Till i Get Mine. Key trick to that sweet exhaust is leaving the cats on

 

Good Choice! I love mine with LTs and no CATs.

 

You are wrong on that one. It will be very noticably louder...in a good way. I remember when i had my car dynoed after header install. I was standing behind the car on one of the pulls and i couldnt believe how loud it was. I had only heard it from the inside. It was unbelievable. Sounded awsome.

 

[You are wrong on that one. It will be very noticably louder...in a good way.[/That is what I meant to say. The leap will be a good one. I can't wait

 

I find it kinda loud inside around town when it's cold; it'll buzz my ears with the windows up as it goes up the rev range. But you're right - NO DRONE at cruise. And windows down, t-tops off, WOT - awesome!! It's always a downer when the windows are up and you can't hear how it sounds OUTSIDE the car.

 

Has anyone tried emailing GMMG lately? I've been trying for the last week or 2 and their email is down or something..... I don't want to wait any long for my GMMG ... I WANT IT NOW! lol

 

Try GMMGinc7@aol.com.

I am going from memory but I think that will get through to Ron

 

Nice man, very nice it's an excellent exhaust, best out there. With longtubes it is HIGHLY noticeable difference, inside and out of the car. You should hear what it sounds like when outside of the car, abso-friggin-lutely amazing, huge difference!

Although i have QTP LT's and Catted Y i would go w/ the Kooks SS setup because of their Y pipe. The Flowmaster merge on the QTP setup creates problems in the case youd like to order a crossmember mounted torque arm w/ a driveshaft safety loop. :'(

 

Interesting. Is the Kooks Y 3" like the QTP? Is ground clearance a problem for you? I want to use Sportlines on my car and I know there will be a drop but I want to make sure that it is not going to be miserable driving over stuff. Do you have pics of your clearance under the car. If you do could you post them?

Thanks

 

looks awesome! only wish i could afford one as well.

 

I m glad you like your GMMG, I had it for 3 month now and adore it
I just came back from vacation and use any excuse to take the car out just to hear it...
I heard only the best things once you put LTs , some prefer cats some then prefer ORY
I want to go LTs and ORY, but for now its goooooooooood.

the most shockign thing to me was how good it sounded from outside, I think thats where it gets it very distinctive popular sound
anyway thats my.02

 

Congrats on the GMMG. I remember when I bolted mine on. I got some pretty shitty gas mileage that week cuz I was staying in gear too long to get the RPMs up. LOL. I'm FIENDING for longtubes now.

 

Hope to have one soon. You seem to have answered alot of my questions. I want one NOW!

 

I have the GMMG and kooks headers and there catted y.I love to drive off into the sunset with the car it sounds amazing.Especially with with a cam!!!Gald your happy with it.

 

when we put gmmg on my friends 97 lt1 we both loved the sound. went through flowmaster, tsp, and magnaflow before that. he's really happy with the gmmg.