Hi,
maybe it will be interesting for you. Year before I imported STi 3 from Japan. It was SUbaru Impreza WRX STi III. MY upgrades on it was AP racing brakes, PE exhaust manifold, PE exhaust, quick shift, Quaife ATB fron differential, HKS SSQ pop off, rear bigger swaybar, water spray on IC, momo 33 steering wheel.
Conversion onto left hand drive was little bit difficult but was sucessfully done. My last creation is conversion to USDM spec 2,5 STi engine. I bought short engine and Im using it on my old heads (some mods required). It was the best mod I have done. Engine is smooth, big torque, big safe power. (I installed Haltech motormanagement before engine instalation). Now engine is in running in. After it I will remove the engine from the car and will be finally mapped on engine bench (i have good connection to people who mapped and build racing (rally) engines long time). (I forgot to say with the new TD05-big 16 turbo.
My future mods: electronic adjustable diff from type R or RA (with elctronic management - differential maps), strenghtened gearset, external turbo wastegate.