Early splitter is on the early GT's, i may be able to get hold of the splitter for you though, because my cousins got a fucked up bumper but splitters ok i think. i'll pm you once i found out Also well spotted with that sensor thing lol!!
Yeah when my cousin first got his GT (same year as urs), it had a little blue switch near this steering wheel. he found out it was also for the turbo mode. Or maybe it was a little mod the previous owner carried out lol...