Hollow/punched Out Cat

[No Crust Racing]

I've heard a fair bit of talk about hollowing out/punching out the CAT in the hope of gaining some power. Now to me this sounds highly illegal given emission laws but I'd think it'd be hard to tell if done right? Has anyone done this themselves, if so what process, did you open the cat or remove the insides through the holes, did you gain any power? What are the risks etc etc.

Cheers

[paulr33]

if you tap it with a spanner or something solid it will ting if its empty

so its pretty easy to tell if its been gutted

also youll have black crap on the rear bar where the muffler comes out

obvious signs of a gutted cut or "hi flow" special cat

[GTAAAH]

i cant see a standard cat being very good for flow even when gutted though, a decent hi flow cat has far better aerodynamics, and is legal, so can only see gutting cats as doing things on the cheap

[T04GTR]

$9000 + gst fine

but. i have seen legitamate cars literaly hollowing out the cat themselves.

ps.. have fun trying to gut the 4x versions (stainless core)

[No Crust Racing]

Surely a gutted stock cat would flow more than normal?

$9000!! WTF lol

[paulr33]

yeah its a 10 grand fine from epa for violation of emissions

[No Crust Racing]

Woah, that's steep... How would they know though? I was under the impression that it would look stock from the outside and if you get told to go do an emissions check you'd just replace it with a stock one?

[(B1) MR_fanny]

i was thinking of the same thing for a while. then common sense hit in and i bought a hi flow. $360 vs $9k. i think it speaks for itself. from what ive been told u just crack it open at the welt joints gut it and weld it back up. if you can get a straight through pipe and then weld a 3" cat cover over it you will get more out of it.

[No Crust Racing]

Hmmm... straight through pipe might be the go too... hmm...

[GTAAAH]

yeh gutted standard one would flow better, but a hi flow one couldnt be much worse, considering larger size in and exit pipes (not adapted from 2 " to 3", and far better flow design.

Although you could always say youve never had it off and i cant see hoe they could prove it wasnt the last owner

[akeenan]

a gutted cat can ruin the flow of exhaust gases... making it not a mod at all

[No Crust Racing]

Pipe through sounds like a good idea.

[Bl4cK32]

yeah its a 10 grand fine from epa for violation of emissions

This is posted all the time.

No one has evidence, or knows anyone that has been done for it...

Just weld a pipe through your cat

[ali-turko]

i gutted mine and gaind bout 17 kw and i noticed the difference, but hate the black smock that comes pouring out

[AndyMac]

For f**ks sake. This question comes up once a month on these boards.

Why f**k with the environment for a bit more power, seriously, its a pretty selfish thing too do.

[Omurru]

Why f**k with the environment for a bit more power, seriously, its a pretty selfish thing too do.

Isn't the average effective life of any cat converter only about 5 years......

[r33_racer]

someones a hippy.

Perhaps spend a few hundred bux and just buy a 4" cat and put that in instead, the extra size surely wouldnt restrict a 3" system. But i admit having cool flames from the sil80 when it was minus a cat was cool fun when doing mountain runs haha.

[Links]

I believe they measure the temp before the cat and than after the cat, there should be a drop as it passes through.. also - it'll flame on backfire..

It's not worth it, there is other things you can do to get power that doesn't cost you $10k in fines..

[AndyMac]

You don't have too be a hippy at all too have a little respect.

Seriously, its generally accepted that not having a cat/gutting your gut with net you about 3-4rwkw - Really worth it.

Now......Time too pour my excess race fuel into Waragamba Dam.

[2rismo]

It's easy to simply measure the temperature of the cat compared to the rest of the exhaust. The temp in your cat is through the roof compared to other sections of your exhaust.

Adrian