will it make 350 hp if i do the right mods, and what mods will work?

yes it will make 350whp on pump gas with supporting mods and good tuning.. there are other turbos that will make 350whp and cheaper.. ex. sbr gt30 -11 or -12 turbo, fp green, deadbolt superzilla, etc.. just do more research ;)

I've seen them make more than that even on pump fuel. Make sure to pick up a FMIC and a header to get the most out of it. It does react a little differently to tuning than the FP turbos so it will need to be tuned by someone familiar with it.

hey God, do you know how's the lag on the SR55 with the STi?