If your going to supercharge it then dont go any higher then 3.55's. 3.73's might be ok and you can prob get away w/ it but DO NOT DO 4.10's WITH A SUPER CHARGER!!. My friend did that w/ his 91 GT, H/C/I and Vortech S Trim and he ran out of gear long before he got to the end of the 1/4 b/c of the 4.10's. 3.55's are great gears if you want to pile on the boost.