Brief Description: Cut cowling for exhaust and made 4” tube.
I used a plumb to find a starting point for the exhaust ports and used a 3" hole saw to start the opening then connected the holes. There was a small adjustment made to the cut out hole and the exhaust now has good clearance. The 4” extension tubes will fit great when fitted to the cowling. I used duct tape on the 4” paper tube and Vaseline for a release agent and I still had to slice down the middle to remove from the 4”tube. The Vaseline was just a mess and I will not use this again.
I used a string and a vacuum cleaner exhaust to blow air trough the 4” tube to see were the sweet spot for vacuum will be and will retest when it's glassed to the cowling.