Which wheels do you have? We need the width to give reasonable suggestions. If they're 8.5", you can't go much beyond a 255 IIRC.
A lot of folks like some of the Nitto's but IMO, it really depends on how... "spirited"... you drive. The OE tires tend to be garbage for anyone with anything much beyond mild driving habits.
07 GT Prem: Alloy, MT, 3.55's, Steeda CAI w/Brenspeed tunes, FRPP Stingers, 275/40/18 Goodyear Eagle F1 A/S on SVT Cobras (OE GT500's), 14" shorty, Wheelskin side scoops & qtr window louvers, A-H rear window louvers, SHR honeycomb blackout panel, Sequentials, Hella Optilux Extreme XY fogs, Silverstars
06 V6: Legend Lime, Pony Package, 14" shorty, Sequentials, Hella Optilux Extreme XY fogs, Silverstars