I did both, 4.30s and a T56 with a .62 6th gear. 2600 rpm at 70 mph with 275/40r17s. Lots of low end grunt for a mostly stock N/A 4.6l DOHC. I had a no talent 600RWHP '03 Cobra owner at Hallett making excuses for why I passed him on the second lap out and he never saw me again.