Sport 500's cost what...$2000? And you get 30 more RWHP than stock. That's not a very good upgrade IMO. At least the T28/T25's will give about a 120-150 RWHP more than stock and only cost in the $1200-$1500 range. Have you seen the wheels on a Sport 500? They're barely bigger than stock... even Kyle said they were waste of money... said that to me like 2 years ago when I was down at SGP getting some work done on one of my earlier Z's.