the 350z has an ecu that cancels out nearly all mods, induction, exhaust etc, prob the only thing that makes any difference is a plenum spacer unless you go FI
or you can buy a piggy back ecu but it all quite expensive for little gain
most mods are for noise and looks
best money is spent on brakes and suspension imo
they handle miles very well, 350zdoc is selling his atm with 114,000 miles oon the clock without any major issues