You bought the 2 seater sports car for the driving ability, power, fun etc but now you would do well to shake any hot hatch off your tail under any circumstances(although the hatchbacks aren't cheap!)
I think they lost their USL with the 370, as back when the 350z was new you couldn't buy anything with that size of engine and grunt for the money you were getting that for. Now you go to look at the 370 and you have a host of choices, you can sit yourself in a boxter or the cayman for similarish money.
I would bring out the Z and try and have as much power for as little money as possible! but I am all about the POOWWWAAA and wave your willy stats