the differances between jspec gsr and asopec gsr are
Rear LSD was an option only
Rear wiper standard in jspec
Antenna in boot - not in drivers door pillar
Rear seats (jap are non fold down)
Rear seat rear support (its a v-brace)
Front strut/chassis body braces/plates (stiffens body) pertains to Evo models only neither jspec or aspec gsrs had these.
Front Radiator support (has braces for evo front bar) pertains to Evo models only neither jspec or aspec gsrs had these.
Brake booster is same in both gsr specs
Twin pot front brakes (276mm diametre rotors) pertains to Evo models only neither jspec or aspec gsrs had these.
Intercooler spray + switch incabin (same as above)
Electric fold in mirrows
Recaro's with mesh head rests
MOMO 4 spoke steering wheel
Digital Climate Control
Aspec was detuned for aust so jspec had a bit more grunt
Jspec ECU didnt come with eprom, Aspec did ie. the ecu you want for getting a chip
Fuse box on right hand side is different, also aircon lines differ
Options on the jspec were driving/fog lights
Jspec had small lights on frt top of L&R guards that turn on when parkers or headlights are in use
180km jspec speedo aspec is 240kms
Jspec had remote drivers door infared in door key and door handle
Jspec colour coded door handles
Jspec had speaker grills in the door skins like evo's