Gmmg Intermediate Pipe?
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Staging Lane
Joined: Sep 2013
Posts: 81
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Gmmg Intermediate Pipe? Don't know if this was the right section to post if not sorry. Question. I bought a gmmg exhaust a few months ago from a guy in Van nuys at the time I didn't know anything about exhaust systems I'm catching on to everything very quick now tho. Anyway when I bought the exhaust I didn't know it came with the Intermediate Pipe which I didn't receive I went to get the exhaust installed today an when it was on the lift I realized that I needed that part. The muffler guy just cut through the stock Intermediate Pipe an welded it on the gmmg catback sound good when started an idle but raspy as hell anything above 40mph from what I understand it's not going to be raspy on a bone stock ls1 only after you install Lts an ORY which I don't have so my question is will this decrease any hp that I would see with the gmmg i pipe an do you think that's the reason it's raspy. I pretty sure there not going to sell me jus the I pipe so does anyone know where I can get the 3inch I pipe I believe it's 3 inch if I'm not mistaking
The inlet of the GMMG pipe is 2.75" just like factory. You could likely just buy a mandrel 3" I-pipe from any catback and have your muffler shop weld it in -- but if you want to retain the slip-fit connection to the y-pipe then you'll be retaining the 2.75" inlet.
As for rasp, I personally think GMMG sounds like poo with LT's and ORY. I liked it on my old SS as just the catback. That's why that stuff is subjective
As for rasp, I personally think GMMG sounds like poo with LT's and ORY. I liked it on my old SS as just the catback. That's why that stuff is subjective
Thread Starter
Staging Lane
Joined: Sep 2013
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Do you guys think that using the stock I pipe will cause any hp/torque lost and would it sound better with aftermarket I pipe it should be more free flowing right?
I don't think you'll notice any difference on a bolt-on car. If it were me, I'd simply run it the way it is until I felt like switching to duals -- or just put a cutout on it!
On The Tree
Joined: Feb 2009
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I have a similar setup that isn't gmmg, but i was unhappy with a similar sounding rasp that suddenly appeared in the 2500-3000rpm range. i had a roughly 28" dynomax bullet put in the I-pipe and it made dissappear about 90% and quieted the exhaust from idle to redline by about 50%.
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Staging Lane
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Brett Foote
Joined: Nov 2003
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From: Wichita KS / Rancho San Diego
It'll flow a little better. Tone won't vary much. The difference won't be huge; it'd be like installing a full GMMG catback versus just replacing the muffler.
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Staging Lane
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Teching In
Joined: Apr 2013
Posts: 13
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From: Delaware
Gmmg exhaust I have ARH LT's with the catted y-pipe into the GMMG exhaust on a mild cam 2000 SS. Yes even with the high flow cats still raspy so I installed a chambered pipe in place of the I pipe. (classicchambered.com) part #3026sb perfect size for I pipe. Got rid of the worst of the rasp and gave it a badass tone. Man I love how it sounds now! Torched 02 TA had an awesome post on how to eliminate raspiness with the GMMG that helped out. As far as hp I doubt it's enough to notice big changes.
