k i know that the uppipe and ecu programing are the most recommended mods for wrx. but i live in california. so i guess what im wondering is how badly will an uppipe effect emissions? can i just add another cat downstream of the turbo if need be to pass smog? i dont want to change that pipe every two years ya know?. do any of you have a modded subby in cali? if so how closely do they look at the up pipe on visual inspection?
up pipe is not a power mod, it's a safety mod and something you don't need to worry about at near-stock power levels. It's a mod people do before changing turbos or for longerm safety at stage2.
The power mods for you are the ECU and the Downpipe. The downpipe is much more visible to an inspection than the up pipe however it's possible to get catted ones. How... literal... the inspection shop is about the rules will determine if they pass it. It's quite possible to meet all emissions requirements with a much less restrictive aftermarket catted bellmouth downpipe.
yeah wasn't too concerned about power gains more or less concerned about sending chunks of the cat through that nice expensive turbo. as other people have already put prevenative maintence, but i still consider it a mod.
Aftermarket downpipes are incompatible with the stock heat shield. You either have to cut it so it fits with the new downpipe, buy an aftermarket heatshield, make something yourself, or simply leave it off. Most people just leave it off.