I just thought I would ask as I figured someone may have already checked it out. I have not gotten all the way up under the car yet, so I have not had a chance to measure it for myself. I figure it will probably be 2.5 inches. Let me know what you can, otherwise I will post my findings after I have time to get under the car. Thanks...

Where'* GXP Venom?

John..... you've got a pm coming.

Hang in...someone is on their way. Probably 2.5...but we'll get you a real answer.

LOL, Bill....got your PM- kinda busy with legal issues and havent been on as usual. Yes The GXP has a 2 and 1/2 inch exhaust, Stainless. The cutout Daytona brought to mind requires the cat to be moved towards the rear to get the cutout in front of it- ( if that is what the question leads to.

The Muffler system was Corsa in the preproduction concept GXP back in 01-02 but havent been able to confirm this on the production cars. The entire system is stated as refined and engineered to remove any obstructions thoughout by GM just before production so I doubt any real headway can be made with headers or wider pipe given the limited Hp mods available to the average person. And the main reason for the throaty sound of it stock.

The exhaust cutout may still give some added Hp. ..In a discussion with Bill Wren I am in agreement that the cutout should be engaged shortly after the launch. some back pressure is good from a start through the low RPM'*. I intend to install the cutout and tie it in to my nitrous control and trigger both as I pass the 2500Rpm point in a launch.

But with all my DMV problems right now and my cosmetic mods for now finished The Venom is going on wooden blocks and a cover put on her.for the time being till the next show. I surrendered my license yesterday and next hearing isnt till Aug.2. This old stubborn street racer is retired.

Thanks for the replies and confirmation on the 2.5 inch I-pipe. That sounds great regarding the production exhaust and it indeed sounds GREAT too - Ha! I knew about the pre-production catback being made by Corsa as well and I gotta say - the actual stock setup seems to be a mirror image of the pics I have seen of the pre-production GXP. That combined with the terrific stock sound - especially on WOT runs, sure makes me think it could actually be Corsa hardware. That would definitely be a nice touch by GM and Pontiac. When I do get under the car, I will look it all over very closely to see if there is anything that might indicate that it was made by Corsa.

Sorry to hear of your DMV issues Venom. I don't know any further details if they were posted - but good luck in getting things cleared up.

And let me clarify once again, that I planning to mount my cutout just ahead of the Y to the mufflers in the REAR of the vehicle. A cutout can be placed in a number of locations with minimal sacrifice of gains depending on the application. For a purely strip car - many place the cutout right after the header collector - for a street car though, depending on how the exhaust is setup and whether the computer programming has been edited or not - you will want to mount the cutout AFTER the converter(*). Once that decision is made, you might as well try to mount the cutout as far back in the exhaust system as possible while still being placed ahead of the muffler(*). This will greatly reduce interior noise and vibration as well keep hot exhaust gases from being dumped under the belly of the car and possibly affecting the floorpan, fuel and brake lines, electical wiring or connectors, or even suspension pieces. I may need to use a small portion of exhaust tubing off of the cutout to direct the exhaust gases fully under the rear suspension. This mod is about the last thing on my to do list for the GXP right now though - so it will be a little ways down the road. But for a heads up to anyone else interested, there is a supplier on eB** that offers the QTP Electric Cutout + QTP Stainless Steel Cutout as a package in various sizes at a discounted price.

But I will be sure to have pics available when I get this put together!

Corsa would by my guess as well. This exhaust system was designed exclusive to the GXP Bonneville. This is probably why the Exhaust note on my GXP blows away the SS impala I drove with the 5.3 as well as the 5.7 and 6.0 GTOs exhaust sounds. Shame they could not have done a trud dual exhaust on this Fwd car.

On all the other 2000+ H body vehicles, the brand of the mufflers/exhaust is stamped on the mufflers themselves. The stockers on the SE/SLE/and SSEi are made by Bosal. See if you can see Corsa or Bosal anywhere on the mufflers.

Smart thinking................let me check

Well I put 130 Lbs of air to my rear bags and crawled my big ole self under the Venom and lo and behold.... It is a Bosal, should have figured it though. Corsa for show but a regular supplier for production.... At least it'* stainless, though I have to say my 'lil sister can mig weld better than what I see under my car. Attrocious welding job. And you wouldnt believe the rust that already going on under my car. Going to have to get some undercoating before I cover it up.

Venom,

I like the exhaust note on the GXP but would like to have it a little better. Any suggestions?

BTW, still pretty new to the club but have to say, Damn, that car of yours looks good. Keep up the great work.