Now that the Cowling lip is on, I had to trim the upper perimeter of the SS firewall down to get it to fit. I also drilled the 2 holes required for the ground Bus bolts to pass through. I found that drilling with regular bits is HORRIBLE. BUT, using a step drill and it was like aluminum. Easy Breezy. I then polished up the edges using the disk sander. Now the bottom with need the same treatment after the lower cowling lip goes on. Coming soonnnnnnnn