t61

What can I do to make a reliable 500whp? I have a t61 turbo from CX Racing and am thinking about getting 750cc Injectors but I am fairly new to modding cars and am not sure where to start.

My turbo seems to be leaking oil? because I found oil leading up the intake pipe to the turbo and my car smokes a lot when I start it up. Would it be worth getting a turbo upgrade such as a the cxracing t61 with stock internals or just get another stock ct26