PontiacBonnevilleClub.com

Hey everybody.

I have a 2005 GXP and wanted some opinions on something.

I love the way the stock exhaust sounds but am wanting to pursue something a bit louder and a bit more aggressive.

Do you guys know what the internal construction is of the stock mufflers?

multi chamber? perforated tube with insulation? no insulation?

My neighbor gave me her very low mileage factory mufflers off of her 2012 Shelby Cobra GT500...and I was thinking for S***'s & giggles that I may put them on the bonneville.

They are probably similar construction to the stock mufflers, they are nearly the same width and length but are thinner bodies so they should be a bit louder, and hopefully more agressive.

Any thoughts?

If it gets down to it I'll at least use the really nice round tips to replace the crappy quad factory tips.

Welcome!

Since you have a GXP you can't really do anything to ruin the sound the Northstar makes. But I can't wait to hear what the Cobra mufflers will sound like if you do choose to go with them. I have a feeling that you will have the same kind of the tone you have now, just louder.

Yeah, I know since I'm providing everything it will be cheap to install and if I don't like the way they sound I can just swap them out for glass packs down the road...

Just the way better looking tips has me excited.

Magnaflows

http://i605.photobucket.com/albums/tt14 ... 575109.jpg

Someone on the shelby forum I signed up for provided this picture of the opened up muffler from his '08 shelby.

Looks like an uninsulated turbo muffler.

Any idea about the internal design of ours?

RogueSSEi wrote:Magnaflows

These are free...Magnaflows are not...unless you have some to give me.

The only problem I see is that ours are offset input and center out.

I'm pretty certain that any solution you put will sound good. It's hard to mess that up on a Northstar. The question becomes - how much drone will you have and how much you can handle.

On the cheap end you can get good sound but will have drone - on occasion you will get lucky with your piping/muffler combination and it'll work out to be quiet. If you want to drop four figures on a new Corsa system (Part number 14151), it'll scream like nothing else and be drone-free and quiet when you're not pushing it. Construction wise they are straight-through but Corsa works some sort of magic to eliminate drone. They also add another muffler/resonator right after the cat. Many here have seen this before: http://www.youtube.com/watch?v=YlKgtt8jlWc&t=45s&hd=1

Well the shelby at highway speeds is fairly quiet, and didnt drone and it had a way bigger supercharged engine, and ran at 3,000+ RPM at hwy speeds to boot.

these mufflers are ofset on opposite sides. But I would be putting them in the stock locations and cutting then using some pipe from the muffler to the tip so aligning it wouldn't be all that hard. Even if it meant flipping them over or switching sides r to l.

There are lots of dynamics in an exhaust system that determine whether or not it'll drone. The length, diameter, and bending of the pipes, the location of the mufflers, the engine, and so on.

Without going through extensive R&D, there's pretty much only one way to find out...

Oh yes I understand all of that.

I'll have flanges and bolts installed so I can swap back the stock mufflers or even glass packs if I feel I need to.

Does anyone know what the stock pipe size is into and out of the muffler on a GXP?

2.25"

I had Magnaflow on mine. Loved the sound in general, and pleny of videos of this setup on both my car and Jovan's (Sleiride03's), V6 '03 SLE, out on my Youtube channel.

My parts list;
2 - 12225 Magnaflow Mufflers
2 - 35121 Magnaflow double walled, angle cut, beveled edge tips
2 - 1ft lengths of 2.25" stainless, bent about 60* (to bring the tips straight out the of back of the car from the angled mufflers).

http://www.youtube.com/user/CMNTMXR57?feature=guide