stoessjc

I replaced the entire exhaust system on my base 2008 with a Z06 exhaust (manifolds to mufflers). Now I am putting the stock back on to get the emissions recall performed. I would like to keep the Z06 H-pipe and mufflers on the car. I noticed, with the stock manifolds and cat pipes, that there is about 2" of space between the Z06 H-pipe and the stock cat pipes. Also, the stock cat pipes are about 5.5" center to center, while the Z06 H-pipe is 5" center to center. Lastly, the Z06 h-pipe is 3", the stock cat pipe is 2.5".

Has anyone done or heard about fabricating an adapter that will mate the stock cat pipes to the Z06 H-pipe?

PA_BLUE_C6

Cut off the end off the 2.5" cats, use the 2" space to adapt up to 3". When done, the Z06 manifolds will bolt back up.

schpenxel

I thought the whole point of the recall was to add a set of cats to the H pipe?

There isn't a "regular to Z06" exhaust adapter out there but any competent exhaust shop should be able to make it work.

I'd make sure the recall isn't going to replace the H pipe anyways first though.. if so then obviously you'll want to swap the whole system back to stock before taking it in.

stoessjc

Response to my other post says that they replace the mid pipe (H pipe), because that is where the additional small cats go. Now my question is if those new cats are bolted or welded to the new mid pipe. If they are bolted, it might be possible to adapt the Z06 H pipe to fit up to the new cats and thereby keep the Z06 mufflers. If the cats are welded, then it is likely a violation of emissions to modify the mid pipe in any way, even if it is on the downstream side of the additional cats.

I will proceed with returning everything to stock in order to get the recall completed. Then I will evaluate if it is possible to modify to get the z06 mufflers back on the car. I like the sound of the open muffler that I do not have with the stock mufflers, since my car did not have NPP.

Mike's LS3

Converters are welded onto the mid pipe all under one part number.

Install stock exhaust, do the recall, then have a muffler shop install after the mid pipe to Z06 mufflers. Now you will be CA emissions compliant and have the Z06 mufflers again.

schpenxel

Correct. Converters are built into (welded) into the new H pipe.

stoessjc

If the new H pipe follows the same path as the stock one, there is a significant difference in the spacing at the end where the mufflers attach. The Z06 spacing is much closer than the stock mufflers. I would assume that any modification to this new H-pipe would be considered a violation of emissions, since the cat is welded and it is considered one part, correct?

So, if I modify the new pipe to fit the Z06 mufflers, am I potentially creating a emissions compliance issue? I know the chances are slim that someone is going to look under the car (considering this is literally impossible without a lift or jacks, and most testing stations do not have this equipment readily available).

96GS#007

What you're proposing will be an abortion of a solution. You're going to have the 3" Z cats going into a 2.5" intermediate pipe which will then go to 3" Z over axle pipes. The spacing/length is different at both ends of the pipe, so you will need adapters to connect it to the cats and adapters to connect it to the mufflers.

In addition, it is highly unlikely the dealer will hack the replacement pipe to get it to fit. I doubt they want the liability.

As someone else suggested, the best solution is to swap the stock exhaust back on and then swap back to the Z exhaust.

Another solution is to see if you can find a friendly Service Advisor that will allow you to bring them a stock '08 intermediate pipe and exchange that for the new pipe without actually putting it on the car. This is a long shot, but you never know.

In case you're wondering what the new pipe looks like, in the pic below you can see my 2013 intermediate pipe in the foreground vs a 2012 ZR-1/Z06 intermediate pipe in the background. By looking at the spring hanger, you can tell the length differences between the two at the rear and since they are lined up, you can see the difference at the front.

One last thing....the '08 base pipe has a different angle on the passenger side vs the later pipes. As such, the '08 pipe may not align to the Z mufflers via a simple straight adapter.

schpenxel

Indeed. Just have to recall done, get your inspection done, swap to whatever exhaust you want and be good for a year. It's not a hard swap.

Steve Haefner

Why do the recall? Keep what you have, my .02

schpenxel

No choice in CA. Have to do emissions recalls or no registration for you!

Steve Haefner

Ah fun times

Boomer111

Any time you alter any part of the emission system you are in violation, technically speaking.

I got tired of the game and went back to stock, adding the axle back which is legal.

California just isn't friendly.

ls1121

I would just leave CA. Come live in America with the rest of us.

schpenxel

Haha.. Indeed.. but not always an option

Boomer111

Remember the recall replaces the down pipe. This will require stick manifolds. This is what I dealt with. Tired of switching, staying stock up to Corsa axel/cans.

Plus a tune after the GM reflash when going back to the Z06 set up.

OH THREE Z

Bump

Whoops... bumped the wrong thread

schpenxel

Why?

HOXXOH

Assuming you're fine with the required recall, but want to retain the Z06 mufflers, simply cut the stock mufflers off your OEM pipe at the muffler and do the same with the Z06 muffler and weld it to your OEM pipe. If you look closely, the last inch of the 3" Z06 pipe necks down to 2.5" anyway. At that point the only change is the muffler itself.