Mybluey

I recently had a GMMG exhaust installed on my 01 SS M6 and it sounds awesome. It's everything everyone says it is. My only problem is a vibrating noise I hear. Happens after the car is warmed up. At around 900 rpm's, which is just above idol for me, I get this weird vibrating noise out the back, almost like something banging the underneath near the back. It happens when I'm coming to a stop and also when I'm accelerating from a stop. I looked underneath and everything seems tight. Is there something inside the chambered exhaust that if not installed properly would cause this? or is this normal?

Anyone else have a noise like this with their GMMG?

Thanks!

FenixSS

iTrader: (3)

I had that too, it went away after I 'broke it in'. It was about 2 weeks of daily driving and now it's gone. Also I only heard it on cold mornings, lol, I'm not sure where you are but a cold morning start to us here is like 60 degrees.

Mybluey

Hey thanks for the reply. That would be nice if it just went away, although I've had it on for over a month, so I wonder if it's the same problem. Yeah 60 degrees sounds like a great start to the day, but I can't complain Los Angeles doesn't actually get too cold.

Anyone else have similiar issues?

Thanks

Smallwood

It may be hitting the heat shield on the passenger side, if so you should be able to fix it by adjusting the height of the system.

Xerxes

iTrader: (1)

It's the heat shield. All you have to do is beat the shield so that it will clear the exhaust. Make sure you have about 1/4 inch space between the pipe and heat shield.

Damian

iTrader: (89)

If you're standing behind the car, look on the pass. side up underneath where the exhaust pipe is exiting. See if that straight piece of pipe is touching that lip coming down off the body. I've had 4 catbacks on my car and they all hit this lip at first. I finally just bent the damn thing upwards all the way across....


josh

Mybluey

I hope that's what it is, makes total sense. It does have that thinner metal sounding vibration noise. I didn't think the GMMG would make a sound like that or else why would everyone rave about it so much.

I'm going to kick that heat shields *** for making my car sound like rice.

Ron@Vengeance

iTrader: (51)

Mybluey, Right above the axle, where the I pipe crossed over theres a very tight point bewtween your exhaust and the heat shield. Pry up on the heat shield just a lil and your noise will go away. Its hard to catch all the tight spots when installing the catback.

Glad to hear you are enjoying the exhaust

wild thing

iTrader: (2)

I love my gmmg, put some long-tube headers on it and it will sound awesome!

Trans_AmGuy

And ORY pipe!

BLOODTA

iTrader: (19)

What kind of power gains can be found with the GMMG exhaust?

Mybluey

It was the I pipe hitting the heat shield just after the rear axel. It was an easy fix and now the sound is truely awesome, no more vibration noises. Thanks Cammin BeaSSt and eveyone else for your input, this site is the best!

As for power gains with the GMMG I can't say, haven't had the car dynoed. But it does feel faster than the SLP dual/dual set up I had, so I imagine the GMMG flows better. Whatever that's worth.

Later

1BADFNZ

how bad is the interior noise level and resonance/drone with GMMG LT's and ORY??

Trans_AmGuy

It all depends on how you drive it. If you keep the RPM's up then its loud on the inside... under normal conditions its not very loud at all. I only have a slight drone at ~2K RPMs but I hardly ever stay in that RPM range so it doesnt bother me at all.

Smallwood

FWIW I only gained 1 hp over the GMMG with a cutout.

JackZ28

The GMMG rocks! I had the Corsa before, and then after going through 2 mufflers, decided to try something BETTER! I picked the right one! I have a couple sound files on my site!

1BADFNZ

I have the Corsa on mine right now till the GMMG gets here. I haven't had any problems with the muffler busting or anything but it's just too tame for me

I go to our local f body hang out and all the guys with loudmouths drown out my poor corsa. I'll fix that soon enough GMMG, QTP LT's QTP ORY

JackZ28

Well, the Corsa really wakes up with headers and a cam, but I think that's what happened to my mufflers. Driving on the autobahn at 160+ probably did it, among other things.