Tom, I tried the 14x12 on my SuperTigre .90 and MVVS .91. THe SuperTigre .90 only managed 7,000 rpm and quickly got hot, the MVVS .91 turned the 14x12 at 8,200 and ran just fine. I don't understand people having such a problem believing instructions. As you say the 14x6 is a complete waste of the Webras abilities. As with all engines the HP ratings are a joke.