I am going to be doing a redneckperformance C-4 package over the winter. I believe the car has 3.73 in it now. for a dd that's drove on the Highway would 3.27's keep the rpms around 2,500-2,800ish with a 18" rim. Im going to be geting another vehicle to drive all the time due to gas prices but the mustang will still see a fair amount of street/track use. Also what stall should i get with it...?? 3,800? 4k. it will also have a TB and manual VB. I made the Numbers in my sig with the busted T-5. The car should make around 450hp when the tune is finished. Thanks!!