I'll throw this out as food for thought: On a Lotus I owned I bought a full (both discs & calipers) Wilwood kit. I wasn't very happy with it as beyond replacing a single-piston sliding caliper with a 4-piston fixed one (better pedal feel) the actual STOPPING part of the situation didn't change much. After buying the kit though I knew the part# of the Wilwood caliper. To keep things simple (plus I don't remember!) let's say it was a Dynalite with 34mm pistons. Well I bought the next bigger piston size of Dynalite. Then I did it again. The larger the pistons the more clamping force I has able to exert (I continued using the same pads). The bigger the pistons though the more brake fluid it took to move them the same distance, so my brake pedal went almost half way down now. But I tell you what. I ended up with AWESOME brakes!!!