Do i need to mini tub?

Hey everyone.Need help on deciding if i should mini tub my Duster.I want to order my cal tracs but noticed they have ones for inboard springs or without.I dont want to buy twice so i guess my real question is how fast can i expect a mono leaf caltrac setup to go on 275/60/15 M/T drag radials.Just installed a full TTi 3 inch X pipe system and it looks like it would be a small chore to change it up if i want to keep full exhaust and install the inboard kit.Thanks.