the different between gti n R3 on their perfomance is cam, ecu,exhaust system and body spotted (to improved handling)..their chasis are same either with gti,1.6 or 1.3..the difference only body spotted which gti have 100 over, n for sure R3 more than GTi..
and the advanti rims were 5kg lighter than stock GTi...
this is what was told by my fren to me...