[AroundTheWorld]

Good evening folks. I have been lurking these Forums for quite some time while gathering information, but just now registered. I recently acquired a new 22 LT1 A10. My second new Camaro since my first 98 Z28, but I’ve had five Corvettes (C6 – C7) and several other V8 sports/muscle cars. I LOVE loud, rumbling, deep-toned exhaust systems. I opted for the NPP, but it is still way to quiet for my liking (which I knew would be the case). Now I know that I will not gain any significant decibels, unless adding long tube headers, and/or an aftermarket cat-back exhaust system. However, I want to start out by perhaps deleting the two rear unmonitored cats. I know that in doing so will only increase the decibels ever so slightly, but I want to keep my mods right now down to a bare minimum. I have searched these Forums high and low, reading dozens of threads posted throughout the years as to how to go about doing so. It appears like for a number of year, several manufacturers like Borla, AWE, and Corsa used to offer an X pipe that would delete the rear cats and bolt right up to the primary headers. However, the EPA cracked down on them, and no such pipes are being produced. So is the only option nowadays still to actually cut out the two rear cats, and weld in new pieces of 2.75” pipping? If so, I just really cringe at the idea of hacking the exhaust system in such a fashion, but it appears like it is the only viable option, as the NPP exhaust is a single piece all of the way up to the factory manifolds, correct? That is insane, because we had so many options for the C6 and C7 Vette’s exhaust-wise. Any and all input would be most appreciated. Thank you in advance.

[Aaron07]

I believe the only pipes offered for doing this delete both sets of cats. New Era comes to mind.

[Mark114]

Another problem with the “cut and weld” option is that most exhaust shops won’t do it for the same legal reasons that the vendors stopped selling the delete kits. You could pull fuse 51 in the engine compartment fuse block to keep the NPP valves open all the time. It won’t make a huge difference but it’s cheap and easy. Another option would be the Corsa NPP axle-back. It’s substantially louder than the OEM NPP. The down side is that they’re made to order and several members have commented that the wait time is very long right now. You can search the forums for Corsa NPP if you’re interested in more information about them.

[AroundTheWorld]

Thank you both for the two above replies.

Aaron07, I definitely want to keep my primary CATS.

Mark114, also, most of the welding that I have seen from the pictures look horrendous. Further, even the slightest leak from the welds will result in a CEL. If I proceed with this route, I will purchase some 304 stainless steel pipping, and find a shop that can really weld well. Corsa makes really nice cat and axle backs, but the pricing is really steep. More so than long tube headers and retaining the stock NPP. However, the headers will require a tune. Even an axle or cat-back on the Camaro will require cutting the stock exhaust at some point, correct, as it is one entirely welded piece? It is really complicated to mod the exhaust in a sixth gen Camaro. Yes, I will definitely be pulling the fuse. Can you confirm that for a 22 LT1, it is indeed fuse 51? I know they may change throughout the model years.

[WhiteMale]

I often wondered how a muffler shop would feel it let's say you install the cat back and then leave off the 2d cats (ala the Borla cat back) and drive it up there, all open exhaust, and just try to tell them it's too short and can they "fix it"...? A shop might not realize there's any thing missing there and the primary cats are clearly still there.

[Aquarius]

Maybe its me, but this seems like a bad idea just to make your car louder.

[WhiteMale]

There's almost nothing to be gained being having done it and some sort of bragging rights down at that QT on a Saturday nite

[ctrlz]

Originally Posted by WhiteMale

There's almost nothing to be gained being having done it and some sort of bragging rights down at that QT on a Saturday nite

This is not my cup of tea, as I don't see much to be gained here. And you never know when your state might crack down on OE emissions equipment. Since I might be driving the last of the V8 Camaros and keep the car for a while, I think about that.
Here is a thread with some related info:
https://www.camaro6.com/forums/showthread.php?t=501171

If you do have the cats removed I would suggest hanging onto them and giving them to your wife or girlfriend in lieu of an engagement ring or birthday present. The price of rhodium is through the roof!

[zx9rmal]

I had my secondary cats removed by a small local shop that was OK with doing it. Did it make a difference? Yes. Was it significant? No. Do I like it? Yes.

[Mark114]

Originally Posted by AroundTheWorld

Even an axle or cat-back on the Camaro will require cutting the stock exhaust at some point, correct, as it is one entirely welded piece?

Yes, but the cut is normally done on a straight section of the exhaust to make installation easier.

Originally Posted by AroundTheWorld

Yes, I will definitely be pulling the fuse. Can you confirm that for a 22 LT1, it is indeed fuse 51? I know they may change throughout the model years.

The online 2022 Camaro Owner's Manual still lists F51 as "Rear Exhaust Valve PTSQ". You can check the fuse map inside the fuse block cover to confirm.

[Zr8000]

I would think running new pipes and welding them in would be a lot nicer option than a slip on x pipe and muffler clamps

[LT1ornothing]

Originally Posted by AroundTheWorld

Good evening folks. I have been lurking these Forums for quite some time while gathering information, but just now registered. I recently acquired a new 22 LT1 A10. My second new Camaro since my first 98 Z28, but I’ve had five Corvettes (C6 – C7) and several other V8 sports/muscle cars. I LOVE loud, rumbling, deep-toned exhaust systems. I opted for the NPP, but it is still way to quiet for my liking (which I knew would be the case). Now I know that I will not gain any significant decibels, unless adding long tube headers, and/or an aftermarket cat-back exhaust system. However, I want to start out by perhaps deleting the two rear unmonitored cats. I know that in doing so will only increase the decibels ever so slightly, but I want to keep my mods right now down to a bare minimum. I have searched these Forums high and low, reading dozens of threads posted throughout the years as to how to go about doing so. It appears like for a number of year, several manufacturers like Borla, AWE, and Corsa used to offer an X pipe that would delete the rear cats and bolt right up to the primary headers. However, the EPA cracked down on them, and no such pipes are being produced. So is the only option nowadays still to actually cut out the two rear cats, and weld in new pieces of 2.75” pipping? If so, I just really cringe at the idea of hacking the exhaust system in such a fashion, but it appears like it is the only viable option, as the NPP exhaust is a single piece all of the way up to the factory manifolds, correct? That is insane, because we had so many options for the C6 and C7 Vette’s exhaust-wise. Any and all input would be most appreciated. Thank you in advance.

We have pretty new LT1s, I was thinking of doing the same for my non npp last year. Depending on the dealer you go to for any future warranty claims, the dealer can void your warranty from the tail pipe up to the entire powertrain for tampering with the emissions system. Only exhaust modifications post emissions systems are warranty compliant. I decided to keep all the cats and just get rid of the suitcase muffler. Sounds fantastic on my M6 but the automatic guys say it drones insanely. Fuse pull is probably your best bet

[AroundTheWorld]

Thank you all for your replies. When I had my C7, I installed a Borla X pipe that eliminated the two rear unmonitored CATS, and bolted right up to the primary CATS. It fit like a "glove". Doing so made a noticeable difference in sound decibel increase. What a shame that we can no longer do the same with the Camaro, due to EPA regulations. The two rear unmonitored CATS are just for California emissions. However, nowadays, all Camaros are produced being 50-state emission legal. So they all have four CATS. Per my research, the purpose of the rear CATS are to burn unspent exhaust gases during cold starts, before the primary CATS heat up and come up to temperature. What is one to do though? It is what it is.

[AroundTheWorld]

Prior to removing fuse number 51, it is of course to be done with the car turned off, correct? Should the battery be disconnected as well?