add aftermarket wheels, since pretty much all colours work well. Especially dark wheels. Gunmetal or black spokes, possibly with polished rims, would look good. Take a look at the black Ro_Ja R2-5 wheels on Tire Rack. I haven't seen a pic of Volk SF-Challenge in gunmetal on a Z, but there are a few pics of them on a white Supra on MVP Motorsport's web site. Those look good.
Charles Carbon Black '95 TT '02 Honda CR-V "Bustermobile" Carbon Black '03 BMW M5