Increases from Exhaust, CAI, and Tune

FuTuRe is Z

First, you're in Colorado your numbers will be lower than anyone else on this board because of the thinner air due to elevation.

Second, you own a Nismo, that cat back is as good and maybe even better than some of the offered units on aftermarket save the money. If you want to make power simply get an intake (although post MAF tubes and filters work as well) and Z1 headers + test pipes.

With the tune you would run around 330whp down in normal elevation.