Never heard a ping noise, and i really don't thing that flying without the cowl will prove anything since I can fly it with the cowl without a problem, at least as long as I'm using an os plug, but doing that wrecked the ring last time without any real warning.

Luckily I have access to data recorders so I'm going to put a thermocouple on the head without the cowl on, run it till steady state, then do the same thing with the cowl on and download the data to my computer to analyze the results.

I'll share them when get a chance to actually do this,,, my in-laws are coming to visit this weekend...so there is no telling when I can try this.