I did some research after reading someone'* post on the two Northstar engines and what do you know! He was right. The 275hp V8 is better than the 300hp. The 275hp one has more torque at less RPMs and maxs out it'* hp at a more reasonable/realistic rpm level before redline. So I think the GXP would win. Besides, it is lighter and more performance orientated in its design build. Although, I wanted a better overall package, a 6.5s 0-60mph/135mph top speed is pretty impressive for a big luxury sedan. My SSEI would definittely have to bow down without any mods . Good info that was posted. Thanks!

there is no 04 sts. when the 05 comes out it will be more powerful and faster than the 03 sts and 04 gxp. same drivetrain as the xlr, 4.6vvt, rwd, 5 speed auto