I've got the 04 GT with the high output and find that although it cost more for the premium I get a lot better mileage than with regular. So pay with premium or go back to the pump more often with regular. But make sure that if you get the chrome wheels they are in good shape. Mine have really gone down hill and I always clean the brake dust off but nothing seems to stop the flaking and pitting. I was also warned to look out for hte inside corroding.