To me ... and since i track my car often and intensively ... a 1mm difference in an important bar like the rear swaybar makes a world's difference. The way i look at it is like this : a bar that is 1mm thicker and more rigid/stronger vs. 1mm thinner and less rigid/weaker.
In terms of performance, u probably will not notice the difference (especially on the streets). But even if u do, that's when u push ur car to the very limits at the track. And since I only own the Progress bar, I cannot tell u the difference between the 2 and how much they differ in performance. And what I just said above is just my personal opinion so take it with a grain of salt heh.
