Hello fellow rotary fliers I don't usually reply to this group as I've been tied up with the "other e-mail group" but all that aside, I have an idea that I would like to run by you guys as I hear this group is a little more open to ideas than the "other group". I've been reading about these heat issues, I think this might be an answere. Mcmaster Carr has this  part#   8498K35 they have several different types of castable ceramics that have all sorts of properties -200  + 7000 deg F and this stuff is really strong, it cures room temp after 16 -24hrs depending on the type you buy. So what I'm prposing won't necessarily keep your exhaust from cracking do to improper fabrication, maybe we could cast a box around the exhaust to keep the radiant heat out of our cowlings. Maybe??? Tony