Engine Misfire at Altitude.

[basloane]

I would not be too concerned with the FAA swat team crashing your door down for flying above FL200 ( unless they are dressed in bunny rabbit suits ).
I have known of P337s that have flown as high as FL240 for a short periods, and I have done a couple of long flights at FL210 and FL220.
I have been told that the skymaster is probably good for about FL260, but have not tried it. I am guessing that performance begins to drop off significantly at those levels.
The biggest risk is the cabin altitude... When I was a 30-40s something person in reasonable physical condition, non smoker with no health issues I could regularly fly my non-pressurized T-Arrow daytime at 15,000 with no ill effects. When I reached my early 50s, I tried a flight at 15,000 in a Bonanza and ended up with a pounding headache.
In any case, best to have Oxygen standing by......
As for ADS-B, we installed a GTX345. For most flights, 978 UAT is probably sufficient, but one day you are going to want to fly over weather at FL200......
Does anybody know what happens with 978 UAT above FL180....?