You will be very happy. The Roush unit is at OEM like quality. The tune is very conservative from Roush. VMP and Ortiz Performance both have good quality tunes for that blower kit if you want something a little more aggressive.
Your stock drive train will handle the blower just fine if you play nice with it.
1998 Roush: M112'd Aluminum block 4.6L 2V 6 speed track car
1999 SVT: Mostly stockish
1970 Mach 1: Resto-modded monster
2000 Roush #5004 - World's FIRST M112'd V6 Mustang. Sold, but not forgotten.