Attn '02-'05 WRX Owners: The Importance of the Uppipe Mod
BBKs on a vehicle that isn't a track car is a waste. If you want to stop faster, get better tires. If you want better feel, look at pads/lines/fluid.
When you talk about a temperature gauge, what are you referring to? EGT sensor (you should have a CEL, if that's the case)?
Ignore eBay/CL. Look to the vendors on the site for purchasing parts.