Installing the upper firewall was pretty easy, with one minor setback. Because I made my turtleback 1.5" taller than plans, my upper firewall (which, following the plans, I had made WAY back in Chapter 4, several years earlier) was not the right size and shape. Rather than remake it, I just shimmed it out and filled it in with scrap material. My upper BID tape from the spar to the firewall slipped a bit in alignment, but it was a bit oversized anyway so it will still do the job. I trimmed it a bit around one of the engine mount hardpoints, but otherwise it's ready to go.