This may fit other year WRX/STi's, not 100% sure but I am 100% it will fit an 04 and 05 .
This kit starts with an Ultimate Racing GT35R turbo kit which consists of a Garrett GT35R turbo with a .82 A/R, downpipe, up-pipe, Tial 44mm WG and CAI. As you can see in the pics the downpipe, up-pipe and Tial vent pipe are all heat wrapped and sprayed. The compressor housing is also polished and the hot side is coated. Next is the HUGE FMIC which is an APS DR725 along with some of there i/c piping and some custom made by Revolutions Performance in aluminum, the hot pipe from the turbo is heat wrapped and sprayed and the cold charge pipe is 3" with a blow-through MAF and HKS SSQ BOV. This is a great kit for someone looking for HP. I made close to 300whp on an STi motor with pistons on only 12psi and 91 octane, on 23psi and 91 octane it made 402whp and on a built motor, 33psi and E85 it made 550whp. These #'s are uncorrected at 6200ft elevation. $4200 for the whole set-up!
Installed in my 04 STi:
Everything that is included in the kit:
Garrett GT35R dual ball bearing turbo
HKS SSQ BOV
APS DR725 FMIC