I'm new to the K500 but I do know a thing about power valves on 2 strokes - They are not a thing of the past but still very much so alive today and still being developed. First I come more from the sledding side of 2 strokes (recently 4 stroke) and modern sleds with 2 strokes run power valves in performance engines, they work to develop a smoth powerful power band, adding hp. They do require mataince, like any performce motor but alot of that can be done with good fuel, good oil and oil:fuel ratio - also run cleaners in my fuels to cut down on deposites on the valves. It's like ordering a car with a turbo and then disconecting it. Just my thoughts