What is the stock compression on the N54? If I were you, I'd run 10.5:1 comp pistons. You should get better off turbo power and a lot better spool up with the turbo's and more power per psi of boost (the turbo's will run in a better efficiency area at a lower boost for the same power you'd get with more boost at 9.5:1 comp). In my stock block Honda S2000, it's comp is 11:1 and I run 35 psi of boost; around 850 whp.
11 E92 ZCP
02 Honda S2000
-741 whp 471 wtq (dynojet) @ 29.6 psi on e85; now on 34 psi, 800+ whp.