200 hours on my engine and my muffler got a huge crack, clearly this is not ordinary wear. Talked to John McBean and his first guess was that the stinger was banging against the engine cowl on startup. I looked and sure enough, saw evidence on the stinger that it had been hitting the cowl. The distance from my stinger to the cowl is 3/8" which would seem like plenty but in a rough cold morning start, clearly that is not enough. Rather than buy another $995 muffler every 200 hours, I think I will increase the distance to 5/8" clearance And while I am at it, going to replace my engine mount vibration isolaters too in case those are shot and causing excess movement.

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