first off:
96-00 EX SI have the big front calipers
96-00 (CX, DX, HX) have the small front calipers
96-00 EX has drums in the rear
96-00 (CX, DX, HX) have drums in the rear
99-00 SI has disk brakes in the rear
the SI shares the prop valve with the hatches (or the DX,HX coupe) because...