First look into the Z boards. They will have a lot more options to consider. One thing ou can do is get a corrected intake manifold. Relatively cheap and will help tremandously in the higher rpm range, and when you go to add more mods for engine performance. Then go over to Central Florida Turbos and have them put on a turbo for about the same as the Nismo package and get twice the power output. Throw some nice looking lightweight rims on there with some sticky rubber, tint the windows and ride the fizuck out.

P.S. The super charger isn't to condusive for low rpm performance, they really shine the faster you spin them.....i.e. the higher rpm range. For city drive you will not really be into the higher rpms to much. Besides anything over 400whp is just not nessessary for the street.