just wanted to know if it safer to get a gutted oem cat than a test pipe. because to me it seems safter because the cops would not know its gutted if you get get pulled over. can someone verify?

 

i think you can answer that question for yourself.. its pretty obvious

yes it looks like you have a cat... but it is still illegal ... do what you want its your car and your consequences

 

i just want to know if the cops have little chance to verifying its a gutted cat besides of the smell

 

I have read that gutting a cat can cause even worse back-pressure (via turbulent flow). It was referring to an open gutted catalytic converter versus the standard honeycomb version. This was in a published book, although unsubstantiated. Can't remember the books title either. You may want to look into it though, before ripping yours apart.

 

my friend gave me his 2000 civic si gutted cat, and i have a working cat on my car right now. just passed smog and looking for a little more power. and to save the life of the cat

 

i gutted my cat and it sounded the same but seemed to help alot with top end rpms. and i got better gas milage. now i have the test pipe dealy but thats on the other car now and it doesnt matter with that its e85 and straight pipe from the turbo (iowa)

 

better hope you dont get caught, i think its around a $1000 ticket,
so if that tiny maybe even unnoticable power gain is worth it go for it, but dont post a thread saying i got a ticket for cat wtf.

 

I remember reading in superstreet that they did a dyno test with a stock cat, then a gutted cat and a test pipe. they lost hp i believe over the whole rpm range with the gutted cat. I personally run test pipes on both of my civics, but then again i dont live in california. our cops wouldnt know the difference between a cat and a donut... my .02

 

no matter where you live, it is a federal crime to gut the cat.

 

there you go....

emissions are important.... LOL

 

Switching to a test pipe is proved to only gain like 5 HP... and that was done on a 99-00 Civic Si with I/H/E. That's only a 1 HP gain over the same test done on a high-flow catalytic converter (which was a 4 HP gain).
http://www.importtuner.com/features/...val/index.html

On your car, I would guess 2 HP at most.

You're really better either getting a high-flow cat or not doing anything at all.

 

sleeve the gutted cat. Find a piece of exhaust pipe, cut a slit in it, squeeze it down a little to fit in the cat, slide it in and expand it. you could make a couple small welds to hold it in place. You could even drill holes in the inner pipe you're adding to make it act as a small resonator.

 

false. gutting your car out allows more exhaust to escape. which intern give you small HP gain.

HP gain is minimal though. and most of it is high end.

 

That may be true, but turbulent flow can be worse than standard back-pressure in some cases.

EDIT: the best idea I see is what thumper64 said, sleeve it.

 

A gutted cat gets you barely any power, and will make you throw a code for catalyst efficency below threshold. Hondas require "heavy loaded" cats and even a lot of high flow cats will throw a code. Like others said, if that little bit of power is worth the repercussions then go for it, but IMO I wouldn't touch it.

 

In Washington as long as your car is OBD2, and you don't have a check engine light on, you pass.

They don't even stick the sniffer in.

 

I had a guy at my old job tell me that a test pipe can cause burnt valves. He was more of a domestic guy, so I'm not sure it applies to us. But it did make me question if the minor gain is worth possibly hurting the motor.

 

what if its a obd1 ecu?

 

Old mentality from the 60s. Not really true with today's materials and engine design.

If you take a completely stock 72 Camaro and run it open header, you can burn an exhaust valve. If you run a 94 Civic open header, it will just be very very loud.

That same type of mentality can be found when you hear "an engine needs backpressure for torque". It doesn't and backpressure is bad for all engines, but it does need exhaust gas velocity, which an overly large exhaust ruins.

 

alright, I thought that was probably the case, but wasn't sure. I know about the whole exhaust velocity thing.