Gearbox; Mosfet, stronger motor, stronger spring, lipo
Hop up; Prowin hop up, PDI barrel, Prometheus flat nub and straight bucking?? I've got one on the way so could test the results for you. R-hop is generally the way to go but takes time to get right, unless you have someone like Proffrink to do the work for you (for a price, but it's worth it.)
After all that's done, use the heaviest BB's that your hop up can lift.