, I understand what you are saying here but, at the risk of being seen as a PITA :veryshocked: a couple things stick out here to me, first you said you got longer bolts to protrude through the casting of the exhaust flange, that you threw away the gasket and that the muffler is a sloppy fit. Yes in that condition, the bolts will come loose and the Nordlock washers will hold fine. I am one to try to resolve the original cause. It seems to me that the manufacturer and designer (DLE) designed and tested this engine and all its parts (yes they test at ideal conditions). But they released this engine with the bolts, muffler and gasket as being sufficient for the job at hand. If properly installed, and with proper fuel mixture (the manual calls for 30:1) and proper engine cooling, minimum airflow ratio being 3:1, exhaust airflow being 3 times greater than air intake, I tend to go with more airflow exit, you can use the gasket and original length bolts and I also use red lock-tight you will not have this problem. It just depends on how you choose to remedy the problem. I try to keep my engines running as cool as possible for extended engine life.
I need to qualify my statement, I am a GM trained auto technician of over 30 years, I have dealt with perceived design flaws many times, mainly when customers put "cool looking" wheels and tires on their vehicles, customers come back to the dealership complaining of tire wear and wanting an alignment under warranty just to find out that the cool wheels and tires they bought have the wrong offset throwing the scrub radius, camber and toe way off from the original design points causing the tire wear.
Just my 2 cents