Running the DLE 20 at really high rpm, then experiencing a crank pin failure is not that unusual? Several with that same experience have written in regarding that, with the same results. I think an engine turning the prop over 9k on the ground is just looking for trouble? Save yourself the trouble and find a bigger prop...

Bowman rings are great, but not a necessity unless you're looking for that last little bit of available performance? My engines, and the others I have first hand experience with, all run just fine without them? It's like any other engine popular enough to have aftermarket parts available for it. These engines are built to a price. ANY component on it can be improved on if you want/need the absolute best.
The question remains, what increase can be experienced, and do you really need it? Not a big believer in aftermarket stuff when the OEM seems to be working fine.

Regarding the XYZ, don't forget about the RCG 20's? Not trying to take anything away from XYZ, but having just one option for service parts makes me nervous....

-Al