hi-flow cat or simply removing the cat? check engine light, etc..

[Kookykrispy]

I just scored a 3" downpipefrom a buddy as part of a trade for some rims I had. On the outlet side, it has a 3-hole 3" flange (header type) that is different from the inlet on my stock cat. I'm currently running a tanabe medallian cat-back system. the Tanabe uses a stock 2.5" flange at the cat outlet and then steps up to 3" right afterward and is 3" from there until the rear exit tip.

I am thinking I have a couple options here. Obviously, the 2.5" cat is a major restriction in the exhaust system.

Since I live in a non-emissions county, so I can legally run without a cat. One option is to make a 3" test pipe and weld a 3" inlet onto the Tanabe cat-back. (I have a mig welder)
I've heard that removal of the cat will make the "check engine" light come on. Is this true? if so is there a way to reset it or re-calibrate it so the light will return to normal operation?

Another option is a high flow cat. How do these compare with a straight pipe? The aftermarket ones are kind of expensive, so I'm wondering if a 3" cat culled from a heavy duty turbo truck at a salvage yard (such as a cummins or powerstroke diesel) might be made to work?


It would be nice for the resale aspect and also if I move to the city to have this car emissions-legal... or at least to where I could put the cat back in place to make it pass smog if I had to.

 

[My96AWD]

I just scored a 3" downpipefrom a buddy as part of a trade for some rims I had. On the outlet side, it has a 3-hole 3" flange (header type) that is different from the inlet on my stock cat. I'm currently running a tanabe medallian cat-back system. the Tanabe uses a stock 2.5" flange at the cat outlet and then steps up to 3" right afterward and is 3" from there until the rear exit tip.

I am thinking I have a couple options here. Obviously, the 2.5" cat is a major restriction in the exhaust system.

Since I live in a non-emissions county, so I can legally run without a cat. One option is to make a 3" test pipe and weld a 3" inlet onto the Tanabe cat-back. (I have a mig welder)
I've heard that removal of the cat will make the "check engine" light come on. Is this true? if so is there a way to reset it or re-calibrate it so the light will return to normal operation?

Another option is a high flow cat. How do these compare with a straight pipe? The aftermarket ones are kind of expensive, so I'm wondering if a 3" cat culled from a heavy duty turbo truck at a salvage yard (such as a cummins or powerstroke diesel) might be made to work?


It would be nice for the resale aspect and also if I move to the city to have this car emissions-legal... or at least to where I could put the cat back in place to make it pass smog if I had to.

if yo lose the cat then you have to either wrap the 2nd o2 in tin foil and put it baack in, eliminate it with certin resistors, or hang it out of the exaust stream. i sugest the first or last option.