The strips to which the cowling will eventually attach call for 3.2 mm(1/8) rivets but the skin was dimpled for 4.0mm (5/320 rivets). the 3.0mm flush rivets sat too deep in the dimple so I made the decision to up size to the 4.0 flush rivet to match the skin. This leaves the upper 3.0 mm rivets for attaching the forward windscreen dash. Attachment holes at the end of the strip did not line up with the skin so I used the rivet finders to match up 2 new holes. I have been adding rivnuts to the firewall for items not listed like the gascolator. I had to procure more grommets and fit for firewall pass through.