ORIGINAL: Slow and Steady
On my DLE 55 the muffler bolts don't bare on the outside of the muffler. They fit within the tube and bare directly on the mufflers exhaust plate. The SAP bolts as we know, bare on the exterior of the muffler box and likely have less holding resistance exacerbated by the engine vibration. That being said, I have spoken to a number of seasoned flyers and they suggest Red Loctite, which has held up on the DLE. If I go with a JTEC it will likely have a bolt bearing design similar to the DLE. It is my understanding that they make custom mufflers. So far the reconditioned engine is holding up and the muffler remains secured. Something to note, my muffler issues with the Syssa engine may have been related to the gear kicking out on my Funtana, causing the muffler stacks to take the brunt of the landing force and causing the muffler to possibly deform. Don't know if any one else has had the same situation lead to their muffler issue. But I thought I would put it out there.
The DLE engines have a side mounted muffler, so the dynamics of the problemare completely different. The engine firing pulses act at a right angle to the direction of rotation of the mounting bolts, so they are less likely to cause them to loosen.
If the problem was simply holding resistance of the bolts, then safety wire would fix the problem.