on my hx40 i got 40lbs plus and dyno 570 so it is def possible to get over 500hp on a hx40, granted it blew up on me after i did a track run i wouldnt waste your time or money on a hx40.... their **** turbos. do the essentials first, gauges, lift pump, studs than worry about stepping into a bigger turbo with bigger injectors. s300 preferably? idk how to spell that word