Hollowed out cat
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Melting Slicks
Joined: Jun 2004
Posts: 3,032
Likes: 4
Hollowed out cat
For awhile there has been an ugly knocking coming from under my vette. I had it on a lift the other day and listening around, and it's coming from the catalytic converter. I was considering a few options, I'll probably replace it with another stock cat eventually- but i was first going to hollow out the cat and just run my vette like that for a while. I was wondering, how many out there of you have done that? Is there any danger to the engine? noticeable HP gain? Just wanna get some opinions. 
Melting Slicks
Joined: Apr 2004
Posts: 3,287
Likes: 7
From: n/a SC
I took the cat off my 94 zr71 (daily driver) when I had to replace the muffler I went ahead and put a flowmaster on it. When this was done the truck had about 140k miles on it so the cat was probably pretty clogged I noticed a pretty big gain in performance. If you're like me when poeople say they noticed a big gain in exhaust work you say ah thats because they WANTED to feel a gain. But honestly I feel I picked up around atleast 15hp. I think most of the gain was from taking the cat off, it also gives it a deeper tone that went well with the flowmaster muffler.
my vette is stock so I don't know how gutting or removing the cat on it would do for performance but on my truck it was a great little mod. I have heard that after 2 years it does somethign to the engine because the senors etcetc know it's not there and all I think thats just BS tho.
my vette is stock so I don't know how gutting or removing the cat on it would do for performance but on my truck it was a great little mod. I have heard that after 2 years it does somethign to the engine because the senors etcetc know it's not there and all I think thats just BS tho.
Melting Slicks
Joined: Jan 2003
Posts: 2,167
Likes: 0
From: What did the 5 fingers say to the face? SLAP!!
Originally Posted by mikey whipreck
Is there any danger to the engine?
No
noticeable HP gain?
No
noticeable HP gain?
I've had mine gutted for over a year now. It was just supposed to be a temporary thing because the car was running rich and I didn't want to ruin another new cat. I've kind of grown used to the sound now, and don't think I'll ever replace it. I used an air chisel to knock all the honeycomb out, then welded a 3" pipe through the center. From underneath, the car looks stock (except for the Hookers
)
