The backs are Nitto 555R's. For the power mine puts down, they haven't made much difference against other street tires. In general, the car feels very sloppy on handling, but my comparisons are a modded Trans Am and the fiancee's new G37.
For a car on the street, the Yokohama Advan Sports do not disappoint but they smallest is a 17". The have an "S-Drive" as well that comes in smaller sizes common on the Z cars. I hear the Michelin Pilot Sport PS2's are in the same league.
Blacking out the trim makes a big difference, as did removing the side markers. IMO, if you painted it yellow with black trim, the bumpers would look best in black.