Do you even read??? ???
The guy had a ver3 STI and he bought a new HD clutch for it but did not fit it, then sold it/replaced it with a ver8 STI (his current car) and now is asking is it possible to fit the 5speed clutch (that he bought previously) to his ver8 STI which have 6speed gbox!
now re, "at least 3500lb", NO, no need for that at all, my previous clutch was 2800lb and was fine ~300kw
simple answer is yes it\'s doable like funky said and you\'ll need what funky mentioned!