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hey mate, i have done it on a N/a 4cyl , i wouldnt recommend it for a n/a car and i wouldnt do it on my r33.

i doubt there is much performance ot be had with a street r33 any ways ?? is there?? it would be very minimal if u had a dump full zorst and a high flow cat alrady.

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Hey guys,

I am aware of punching the center out of a cat is illegal . Im thinking of punching out the inards of my sports cat and replacing it with a 3 inch pipe.

Anybody got any ideas and comments on the matter?

not sure what info your after. you admit you know that its illegal, thats really all there is to it

theres very limited gains to be had

i had one on my 33 T when i first got it

replaced it and felt or saw no difference on the dyno

a very slight deeper note to the exhaust and a little more stinky thats the only differecne between that and a god quality hi flo item

Jimbo

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if you are in qld you will just have to watch out for the hoon squad. when they are doing a blitz they have a epa station setup and they will tell you to go straight to it and escort you there. they did 1 up here in gympie. had it setup for emisions and noise. went right over the car.

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lol i saw "cat punching" and the last post by ctjet, it made me think of something entirely different.

I think the noise must depend on the car. A couple of my mates have had theres hollowed out and it sounds sh!t.

Personally I would just get a high-flow.

Edited by shyster
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When my old S13 was brought into the country, the CAT had been split at the top - gutted out - exhaust went straight through - and finally the cat sat back around the exhaust and welded at the top where no one could see.

Sensor was still sitting in it - though it was ummm loose and rattled..lol

Went to replace it but when I took it over the pits at the RTA for first rego they didnt even test it!

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The RSPCA will be onto you pretty quick for punching your cat.

PS think about what it does to the environment, and whether you are that selfish to do it for the maybe 5kW extra. Just go buy a good new metal substrate cat.

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Hey guys,

I am aware of punching the center out of a cat is illegal.

Anybody got any ideas and comments on the matter?

Yeah, I do believe that punching the innards of a cat is illegal. But I don't know, I much prefer punching cats in the face.

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knocking the car isnt the bet idea

best to get a pipe.

have a look at it all, the exhaust gas would be mising around something shocking, so possible gain... but a better gain from a straight pipe thats evenly flowing

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