trust me, I ran 2 XR2's in a rally championship for 2 years and 15's are shiiiiiiite, 13" XR2 rims are fine, you'll power out of the corners much quicker and handle alot better. I ran standard halfords pads and drilled discs and never had any fade, but it was rally speeds, 40-70 mph, not track speeds, 80 mph+.