There is a thread in the RV-12 area about how the rear window threaded holes should be drilled out #27 before final installation and that this also applies to the RV-14. I checked directly with Vans and yes on P38-03 step 8 ALL holes in the rear window get final drilled to #27 including those that were tapped during the preliminary attachment to the roll bar. I know this was not clearly understood by myself and a couple of other builders that I keep in touch with.