Third cat delete/hollowing

[The01Cav]

Has anyone hollowed out their third cat or deleted it? If so is there really much of a performance gain doing so?

[auquier]

Re: Third cat delete/hollowing

For those that don't know - a third cat was added to model years 2008+ between the engine and the resonator. I kept mine when I installed the GT-R.

[The01Cav]

Re: Third cat delete/hollowing

Just trying to see if it's really worth removing or not.

[auquier]

Re: Third cat delete/hollowing

The person I know that removed theirs is bambamm - sexyg6 says he's going to...

[DroptopDiamond]

Re: Third cat delete/hollowing

IIRC Sam says that the 3rd cat makes a 6 hp difference with his exhaust.

[cookiemonster17]

Re: Third cat delete/hollowing

would exhaust tone change? and any codes be thrown?

[auquier]

Re: Third cat delete/hollowing

No codes, there's no electronics in that cat. It's illegal from an emissions stand point though.

[dre256]

Re: Third cat delete/hollowing

The 2007 GTP 3.6L is rated at the same output and internals are the same as the 08 GXP so I wouldnt think there is a performance gain. As ussally if the performance drops due to exhaust they list it like 07 GTP 252 HP 08 GXP 245 HP but thats not the case.

If you wanted since theres no electronics attached to it, get rid of it and get the 07 GTP flex pipe that bolts from the upper 2 cats to the resonator or have an exhaust shop do it. But an exhaust shop may not want to take that cat off.

[Phenom]

Re: Third cat delete/hollowing

do the 08+ 4-cyls have a third cat?

[DroptopDiamond]

Re: Third cat delete/hollowing

They've got SIX cats all along the system





IDK I guess they would have teh 3rd one also :shrug:

[The01Cav]

Re: Third cat delete/hollowing

Well I hollowed out my cat, no sound but maybe a very slight increase in performance.

[SexyG6]

Re: Third cat delete/hollowing

prob would have been better off removing it, i made $50 off my third cat from my GT at a scrap metal yard when i put my GTR on that

and yes i am removeing my 3rd cat on my GXP b/c i already removed the 2 main ones by adding headers, and i am also unwilling to cut up my stock exhaust which is what would be required to keep it, so im hopeing same will just make mine up as either a strait pipe to with a flange or pipe with a flange and resonator i think i want just a strait pipe to the flange and a resonator seperate since i will probably want one to cut down on tinnyness but want to see before i put the res in.........

when i got a gtr for my GT he only included a small piece of pipe to weld on to the cat, well i didnt wanna keep the cat so i went to get a piece of stainless pipe and NONE of the exhaust shops carry it, so i went to a race/performance shop and they sold me "stainless" which i came to find out either was not or was very low quality stainless b/c it wasnt too long before it started rusting and TRUE stainless is non-magnetic.............so hopefully same will just include a piece like he does on the 07 and older

and btw to the ppl that think the HP numbers would be different if it decreased performance isnt necesarilly true B/C GM does NOT dyno the cars they dyno the stand alone engine which likely didnt have an exhaust anything like on the 6

[Phenom]

Re: Third cat delete/hollowing

Bambamm stated that when he took out his third cat, his MPG's went a lot worse than where they were before.

[uzun1986]

Re: Third cat delete/hollowing

Lets see a pic of this 3rd cat....mine only came with 2

[Phenom]

Re: Third cat delete/hollowing

i believe its number 22..