Torsion bars depends on what you want to do with the car, drag race only use the six cylinder. They will let the front of the lift to transfer weight better to rear, but will not handle good on turns with a big block. To handle on the street you want to go with a stiffer torsion bar. Go with any torsion bar from a .890" good handling to 1.04" which is great for HD solo, road racing or circle track. Depends on how stiff you want the front end.