Thread: Yet another resonator/glasspack question (calling Scotty)

I know this has been posted about 1,000,000 times, and I have seen Scotty's post about his setup about 500,000, but the problem is I haven't seen any part numbers posted, so this thread will hopefully get the information out there for future use.

My car is an 07 Grand Prix GT (Supercharged). As far as I know the catback is all stock, though it is reasonable to think it has been replaced before my purchase of the car. I crawled under the car and measured the resonator as having a 29" body. It measured 31" from the front flange to the rear of the body.

Now here's where the questions lie. I used a set of digital calipers to measure the exhaust behind the resonator and it measures 2.25 OD.
I found a 2.25" ID inlet/outlet, 27" body/31" OAL glasspack at Advance (PN# 24205) Is there enough play in the rest of the exhaust to make this glasspack work?

Next question lies with the flange to get to weld to the inlet side. Do I just need a 2.25" flange? If that is the case Walker has one (PN# 31885.) Is that one okay?

Lastly, as long as the resonator and flange work, what size band clamp do I need to attach the glasspack to the rest of the catback? It may sound like a silly question, but I have read a few reviews saying you need to order .25" smaller than the clamp says? I also assume I would need a lap style clamp?

you need the 2.5 flange with a 2.5 gasket. i bought the 2.5 Gpack because i wanted the 4 inch body instead of the 3.5 that is on the 2.25 Gpack. it was way to big and needed an adaptor piece welded on to fit the stock exhaust. you need the 2.25 Gpack and 2.25 band clamps.
the DP flange is 2.5 also

if you have a factory cat back you'll need the g/p welded in. the stock pipes are far from round really.

2.25 in and out. i got a stock cat back gasket, wet to the local muffler shop, matched and bought a flange there local for 10 bucks.

my g/p was a 32 inch, i cut the inlet tube off and welded the flange to the body of the g/p. the cat back has a couple inches of wiggle room, only thing is the if you need to push it back further the tips may stick out further then you like.

Well, I just thought about it and I measured the studs that come out of the resonator and it measured around 4.1" center to center so that makes sense that it would be a 2.5" flange. Walker PN# 31896 says its a 4" bolt pattern, which shouldn't be an issue. If that's the case then the gasket would be PN# 31337.

I should be able to get everything I need except for the band clamp at Advance for about $40. I might just pay my buddy a few bucks to weld the flange on for me.

Originally Posted by ScottyDoggs

if you have a factory cat back you'll need the g/p welded in. the stock pipes are far from round really.

2.25 in and out. i got a stock cat back gasket, wet to the local muffler shop, matched and bought a flange there local for 10 bucks.

my g/p was a 32 inch, i cut the inlet tube off and welded the flange to the body of the g/p. the cat back has a couple inches of wiggle room, only thing is the if you need to push it back further the tips may stick out further then you like.

Like I said, my resonator body is 29" and its 31" from the flange to the back of the body of the resonator. That means a 31" glasspack will actually be a little short. That means I would have to pull the catback forward a little.

I could order a 24211 glasspack which is a 30" case and 35" OAL. With that I could cut the front inlet tube off like you did and weld the flange there. That would make OAL around 32.5 at that point which would keep from having to pull the catback forward.

Regardless, you don't think I can get away with a band clamp at the rear of the glasspack?

The Walker 2.5" flange is $10 at Advance, so I'd actually be gaining there by not having to make an additional stop.

this is what i used for the flange
http://www.amazon.com/Dynomax-41806-Exhaust-Intermediate-Pipe/dp/B0015KU072?tag=viglink25855-20

Originally Posted by stealthee

Like I said, my resonator body is 29" and its 31" from the flange to the back of the body of the resonator. That means a 31" glasspack will actually be a little short. That means I would have to pull the catback forward a little.

Could just weld on some pipe to make up the difference.

Thats what I was thinking of doing.