Its not the top speed, its coming off the corners where it matters to me.. In my Corolla, the 4.56 just feels lazy out of the hole, where the 5.13 feels alive everywhere (I had a 5.38 3rd member too, but that was nuts). I was using up 5th gear pretty good at Mid-Ohio with the 5.13. I'm glad they made the weight adjustment... Now my former ITA car which was minimum weight when I started eons ago is back to minimum weight in ITB with my 20+ year older fatter body! Just need to get some 6" wheels if such a thing is even possible anymore and I'm back in the hunt 