I bought mine from Jeff Balsamo from CobraFormance, and installed them over the summer. The neoprene is already pre-cut. Jeff's also a forum member. I have the Goodyear "Billboards" and they pick up boulders it seems like. Bit no worries with Jeff's neoprene!
His number is 650-678-7711 (cell) or
hallbalsracing@comcast.net
Respectfully,
Chris