I'm doing some upgrades beyond headers I've done cobb cai, silicone turbo inlet, bigger tmic, invidia dp, 3in exhaust, 20g turbo. The headers are the only thing I haven't found solid info on ive read that 02 through 05 wrx and any year sti headers will work but manufacturers say they won't and that i have to use headers for legacy and they are pretty pricey for legacy specific