It really comes down to the individual car and driver as to what works best. I found that a bigger front bar on my NB Miata didn't help all that much until I replaced the sway bar brackets with the reinforced ones and added DA shocks. However on my NC Miata adding a bigger front bar caused the inside front to lift off as much as 10" so it definitely was the wrong approach there. WRT the FiST I think I'm just going to have to experiment. My educated guess is that slightly larger might help but if you go too big you'll loose traction. As to what the perfect size is I can't say but ideally I'd like something with adjustable ends so I can make minor changes trying to find the sweet spot.