GS exhaust question...
Thread Starter
Burning Brakes
Joined: Jul 2008
Posts: 843
Likes: 3
From: IL
GS exhaust question...
I recently purchased a 2012 Grand Sport. This car actually comes with 4 cats. Two are in the down pipes off the manifold and two are in the x pipe. Is it worth it to replace the x pipe with a non catted one? Will replacing it make my Corsa Sports any louder? Any extra HP?
Melting Slicks
Joined: Dec 2006
Posts: 2,694
Likes: 106
I did, mostly to alleviate heat intrusion into the cabin thru the center tunnel. My understanding is those extra cats are only required in CA (all Vettes are 50-state cars), so I replaced it with an '11 one, so now have all 436 horsies 
. Those extra cats shouldn't add too much restriction, but some for sure. And yes, NPP sounds nicer now with valves open, so you should notice a slight difference as well. And finally, saved 8 lbs. By the way, bought mine from forum member/vendor JJFormato for $115 delivered. Below is the comparison. Good luck.
. Those extra cats shouldn't add too much restriction, but some for sure. And yes, NPP sounds nicer now with valves open, so you should notice a slight difference as well. And finally, saved 8 lbs. By the way, bought mine from forum member/vendor JJFormato for $115 delivered. Below is the comparison. Good luck.
Drifting
Joined: Feb 2012
Posts: 1,256
Likes: 66
From: San Luis Obispo, California
Cool post Elp_JC & that looks like a good addition as reduced console heat would be nice. I'm in CA. with a '12 GS & NPP as well, & I'm thinking the 2 cats already on the headers would be enough for emissions.
So, was the increased sound through your NPP that noticeable, or only a slight increase? It's a very subjective question I'll admit...
So, was the increased sound through your NPP that noticeable, or only a slight increase? It's a very subjective question I'll admit...
Melting Slicks
Joined: Dec 2006
Posts: 2,694
Likes: 106
.And to answer your question, both the center console heat issue and sound with NPP open were improved, but not dramatically. Oh, and I had a slight rattle, and was one of those cats, so good riddance
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Drifting
Joined: Feb 2012
Posts: 1,256
Likes: 66
From: San Luis Obispo, California
Gotcha..thanks for that. I've also been wondering if the two mid-pipe cats would enable you to run shorty headers w/out cats, but still pass emissions because of the 2 downstream cats...?? I'll need to find a qualified shop in CA. who's got some experience w the '12 set up.
SUBVETTE
Joined: Jul 2006
Posts: 3,841
Likes: 93
From: San Diego CA
Gotcha..thanks for that. I've also been wondering if the two mid-pipe cats would enable you to run shorty headers w/out cats, but still pass emissions because of the 2 downstream cats...?? I'll need to find a qualified shop in CA. who's got some experience w the '12 set up.
