Ok, just looked at my catalogue. On purely a pad area/outline:
MG ZS180: 131.6x58.6x17.2mm
Integra 98spec / UKDM:129x55x17.2 (or 16.4)mm (very similar but not the same as MG)
EK9: 148.7x57.7x18mm
Prelude: (as above or) 137.8x53.7x18.5mm
Legend: (as above EK9 or) 148.8x59.4x17 (or 17.4)mm
NSX: As above EK9
So the caliper with the largest pad area is the Legend 3.5 [KA9] 9/99-8/04 but if it's using the same pads as the EK9, that's the earlier 3.5 [KA9] 6/96-8/99
The Rover 620 uses the same pads as the EK9 too.