got a quick question about installation of up-pipe and/or downpipe. on my mustang when i put my aftermarket exhaust on i had to get a chip so that my computer wouldn't go haywire when i put the exhaust on, producing a decrease in horsepower. do i have to do that sort of thing when putting an aftermarket downpipe or uppipe on the wrx? thanks.

no...just bolt it up and gooooooo. have fun installing the up pipe though, that's a PITA, but probably no worse than headers on a v8.

well eventually doing that later down the road will help. the Turbo XS UTEC is a poplular choice for many WRX tuners.

It all depends on whether or not you replace the 3ed cat if you get rid of the last cat you can go a couple of routes to get rid of the CEL. GP moto has a non electric fix it puts a space between the last O2 sensor and the exhaust flow so it is not in the direct flow and tricks the ECU in to thinking the cat is there, the other way is less reliable and that is a resistor mod but most of the people I know who have done this have had the CEL pop back on in a few months the best way is like the above mentioned and have the Ecu remaped my pirsonal advice is to have the ecu tuned not add a piggyback. Cobb tuning and vishnu are some examples