i think even a stock Z is a tad too fast for street to really have fun without gettng unwanted attention. something happens to your head when you mature. it starts reminding you about all the negatives of going fast on street (citations, causing accidents, hurting people, bodyshop, inconvenience, repair bills, etc etc) and it tires you to even think about speeding.
so from that point of view unless you're going to track the car i would say the 370Z is more than adequate for street. if you want to do dyno wars that's you're call but you'll never be able to use it on the streets without offending someone. kinda like running SSD on a slow computer. over kill.