so WA state has emmissions testing .

If i took my cat and took all the honeycombing out i.e. gutted it. would you feel the same sort of gain you would see from a test pipe? also would it throw codes? just wondering if anyone knew the answer, thanks.

 

it wont throw any codes and will increase performance a little with better fuel consumption, just like adding a second resonator box really but the good thing is ( it always looks like it has the cat still fitted ) and Ive seen them pass the UK motor test MOT with a little fiddling with the computer to drop the emissions

 

I think i am going to try and do this in the next couple of weekends

 

So how is this done? Scraping the cat. I need to do something like this for my 02 a4 turbo, the honeycomb in breaking apart and rattling. By throwing the codes, you mean it won't alter the sensors or computer with any notifications or service light? I have thought about the test pipe, but for resale, warranty, and such, I am hesitant.

 

I read a good point in another testpipe/cat question thread yesterday... Since the cat isnt just a straight pipe, if you gutted it, it may cause turbulence causing fluctuations in backpressure which might be bad.
Its been done before though.

 

thanks for the heads up onepoint8tee. Maybe i will just buy the test pipe and install. Then, keep cat as is and when i need to do emissions or i sell the car i can replace.

 

or you could get a highflow cat. it'll be better than your stock cat but not as good as a test pipe, but its completely legal.

 

HFC are also like $500+

 

o rly? screw that **** then just gut it