actually you have 1/4" fireproof hi density foam/aluminum foil insulation planks on yours good to like 2000 deg... plus dampen sound, not sure of brand, reeves sells them.....
Wag Aero sells them. They unroll it to the size you need. It is not marked for holes like the Spruce's is. It is fireproof too. I have seen them installed and they look good.
I'm making some up out of 'Radiant Panel Certified' thermal/acoustic fiberglass insulation material with a quilted vinyl facing on both sides. The vinyl is not plastic looking, more like a fabric. The edges get sewn with a 2" tape, and 'circles' are sewn around the major holes before getting neatly punched out. If you need one, send me a PM or email. supercub180@gmail.com
Source for PA 18 firewall blanket?
suggestions in this thread either out of stock or no longer avail,
looking for either cut to size, or material to fabricate one.
Thanks