My arches are custom made ones buddy. The drama is that the two skins of the vehicle join at the arch ( outer skin of the body work and the inner arch). To gain more room you need to cut away or roll your required metal and then rejoin. Sounds easy but rolling is pointless on anyhrhing over higgy's measurements. It'll form a metal pocket that will attract and hold moister that'll develop into rust very, very quickly. I'm sure I put up a few pictures of what was done to the van in the air lift thread in the suspension and steering section. Have a look buddy and if need be, I'll throw some up on this.