When getting up to the horsepower #s you are looking for the rear bank tends to go lean due to the fuel rail design. There is actually another thread up discussing it now. My AEM meth kit was a pretty early one and they replaced it....but I didn't want to risk my motor....haha.....got me real far anyway. I am in no way trying to derail your immediate power goals, I just air to the side of caution when you are setting yourself up for a $10k motor build(done properly) if there is even a slight hiccup. My advise was to enjoy it at a moderate level for a little bit before pushing the envelope. Plus......there will be no traction for you at those levels anyway.
From what Cody says, the stock rails are good up to 550 WHP. I don't see this being a issue since I'm only shooting for 475-490
NSX's shouldn't be tuned much above 550whp unless the entire fuel system is replaced.