I deburred all the holes on the HS structure and skins. I do both sides of every hole. I like using the debur tool with the blue handle that has a crank shape. I bought a second little debur bit, put it into a hex holder and into a Craftsman screw driver. It helps reach the holes inside of the flanges. And I use the little bit by itself in tight places like the nose inside the skin. While deburring holes I found one that was oblong. It was one of the four holes on the 405 rib that attaches to the 702 spar and the 404 nose rib. I sent email to Van's and they replied that it is of no consequence and I should rivet as normal. But they also suggested that if I ever do get an enlarged hole that the fix is to cut a scrap piece of aluminum long enough to reach the two adjacent holes to the problem hole, and about 1/2 inch wide and rivet in three places like a patch. This is preferred to using washers. Interesting.