Here's the firewall sub panel with both corners trimmed out.

After doing that, I decided to flame test the proseal sample. It was pretty anti-climactic. After blasting for about 10 seconds, the entire layer of proseal flopped down onto the driveway. I can say that had it stayed on it would have generated some rather acrid smoke...reminiscent of burning rubber. I'll redo the CS-1900 test later this week.

After that, I got back to the sub floors. Here, I've matched drilled the forward flange of the left sub floor panel to the firewall sub panel, then added the mounting holes for nutplates.