i have a t3 t4 57 trim and stock k20 with 650 rc injectors what psi can i go to

 

the question can not be answered properly without knowing more about your setup. What type of turbo kit are you running?? What has been done to the motor? is it stock? Is it built??

I would say that your biggest limitation is your fuel system, the 650s will be good up to about 350 max I would say.

 

My 650cc injectors are at like 55% duty with 320whp.