I ran a strip of masking tape down the side of the upper cowling, then marked where I wanted the trim line. Removed the cowl, cut off the excess with my dremel, then sanded down to the line. I re-installed the cowl with the lower cowl fitted under the upper portion. I marked a line on the lower cowl, removed and trimmed to the line. Then, I sanded until I could just see a very narrow blue line. Re-fit the cowl—looks good—it is tight and will need some sanding for a paint line, but this will suffice to get the hinges installed.