Just to complete the data in this thread regarding 26 vs 30mm calipers, the 26mm calipers have a 32mm channel for the rotor. The 30mm calipers have a 36mm channel for the rotor. The 30mm rotors would physically fit inside a 26mm caliper, but I don't think would bolt up due to different spacings.

I don't think that the 26mm rotor has *only* a 3mm vent versus a 7/8" (22mm) vent on the 30mm rotors. If that was the case, the 30mm would be crack city with only 4mm thick friction surfaces. I'll go check mine out later. Cracking is more due to manufacturing at this point.

Also, I really don't think that there is any braking advantage between the 2 setups. You'd only be able to tell the difference if you were continually braking hard enough to fade them. In that case, I doubt you'd ever be able to do that, even, as a 90 Z32 N/A weighs about 6-700 pounds more than your average S13.

Also, FYI, the pads are the same regardless of year, turbo, and rotor thickness.