[mikstr]

IIRC the F4i calipers have the same piston sizes as the SP-1 and 929 (and 98-99 CBR900RR; larger than the SP-2 and 954 FWIW).

 

[mikstr]

while outwardly the same, the piston diameters are different on the Sp-1 and 2 (same as for the 929 and 954). This topic has been covered a few times (with appropriate MC and caliper piston diameters listed) on the Superhawk forum.

 

[mikstr]

Here is a partial list for you (from Superhawk forum):
2003-2004 CBR600RR mc 11/16” (17.4625 mm)
caliper pistons 32mm/30mm

2000-2001 CBR929RR mc 19mm
caliper pistons 34mm/30mm

2002-2003 CBR954RR mc 11/16” (17.4625 mm)
caliper pistons 32mm/30mm

2000-2001 RC51 mc 19mm
caliper pistons 34mm/32mm

2002-present RC51 mc 11/16” (17.4625 mm)
caliper pistons 32mm/30mm

1999-Present CBR600F4(i) mc 5/8” (15.87mm)
caliper pistons 34mm/32mm