First things have u tried uprated discs and pads eg black diamond turbo groove etc?? next is the cossie conversion which are 288mm discs mad 4 it do a conversion using your standard calipers for about £175.. or u could go the whole way and fit cossy calipersm 2 but they are expensive. Next is in my opionion the best conversion using focus st170 discs and calipers they are 300mm discs but u need a minaman of 16inch wheels 4 them 2 fit. this coversion costs about 300-350 depending
hope this helps....