Ummm...isn't the std master cylinder on a 916 a Brembo and aren't the standard calipers 4-potters? If so, then the std master cylinder should be fine imo. FWIW I have never noticed a deficiency in the std Goldline calipers for road or track use. I would recommend better fluid, better levers (with less slack and wobble in them), pads (Performance Friction), discs (cast-iron floaters) and brake lines for track use though.
Calipers would be the last thing I changed.