As above standard your looking at 10.5>11 psi stock.
Depends how much you want to spend really, I managed 250kw with stock everything and a tune on 14PSI (with an exhaust camgear), mind you i dont run 14psi 24/7.
Given you have a set of N1's installed, might be an opportunity to grab a set of AFM's/Injectors and a fuel pump and push for 270>280kw.
Probably wouldn't hurt to grab an exhaust camgear aswell while your at it.