R31 skylines from S1 and S3 can be interchangble with each other as a proud owner of a 31 skyrine Ti i have conveted my block taillites to S3 hotplates and the wiring but u must have the S3 garnish to compleat the S3 upgrade
R31 GTSR's came out with the RB20DETR made for the group A racing and in race trim had 400hp
S3 and the Import R31 can be interchangble