Hello,
to briefly answer your questions:

1) Try contacting Dub Jett directly (http://www.dubjett.com/contact2015.html). Dub currently takes care of the entire management of the business, including the RO-JETT line.
2) Check that the mating surfaces are PERFECTLY flat and tighten the screws firmly (but not to death) and try not to tighten one screw stronger than the other. ONLY to eliminate the problem of small leaks it can be useful to use a very light film of silicone sealant.
3) If the air can flow freely around the exhaust system, no special precautions are usually necessary. If the tank is very close to the muffler it can be helpful to isolate it (perhaps with a sheet of balsa and/or with a sheet of heat reflective material) to limit the heating of the fuel, in any case try to favor the air flows.
I hope this is useful.

Massimo

How can I stop the screws that hold on the exhaust header from working loose?  and 3) The exhaust header gets VERY hot and its inside the fuselage. What precautions should be taken to protect the fuselage and internal parts from the heat? This is the first time I've installed a rear exhaust engine in a full cowl. It's a RoJett BSE 40 RE and I'm using the header muffler not the tuned pipe.

I have never used a header muffler, but I have had no problems with headers coming loose. As long as everything is faced off flat and square and the usual sealant the is in place, they seem to really hang in there. I do use lock washers, and the 5-40 screws give plenty of torque. I also am pretty sure I am getting sealant on the screws, which probably holds them a bit, too. All that mass just hanging off does makes yours a tougher problem.

I don’t know what to say about heat. I am surprised that it gets extraordinarily hot in a stunt plane application. And I don’t know for sure what sort of cooling setup will be required. One thing we found in the first few piped flights is that you couldn’t have lots of cylinder cooling outlets because it let the air out before it got to the coupler and pipe which tended to overheat the pipe.

 Brett

  Charles ,
  I use a split washer & an internal star washer on each bolt, run it a minute , recheck , retighten . Then check again after a couple flights. Usually have to custom cut the bolt because of the double washer . I'd try to support the muffler someway. I just had a custom header cut & welded by Dub within a month  he is still open.
  John L.