I personally wouldn't want to run much more than 430bhp through them.

Easiest way is to drop the c/r (machining the pistons), fit four greys, fit relevent chip, 3 bar MAP sensor, -31, wind the boost up and Bob's your Mother's brother.

500+ bhp is easily achievable with headwork, different cams, connecting all eight injectors (changing for greens), but I would want to do this on a brand new 200 block if it was my car.