Some how I omitted one of the most inboard ribs, (between 2nd and 4th rib) so I preped and primed,match drilled and installed it Drilled holes for Pitot line (SafeAir kit nylon line) and inserted snap bushings that came with kit. Also step drilled (3/4) " holes for electical conduit from Van's. This stuff is a !@$# to get through those holes. I finally used my swivel deburring tool and ran that around the hole about 8 times and it made it so that's its still snug, but easier to pull through 15 ribs!