You might want to try the APC 9.3 x 3 on that screamin Jett first and see what it tachs before you bolt on the 9 x 3.

I am running the OSFX with a Combat Can. I use the APC 9x3s here at mile high altitude. It seems to me that the MAS flexs and looses enough pitch angle that it looses it's bite on this thin air, the APC doesn't do this and pulls me through the turns better with general better speed overall. Last year at the NATs - whats that elevation, 500'? - the fat air slowed my prop speed down and my speed overall. I went back to the MAS which gave me my rpm back along with the speed. I have no radar gun or engineering degrees to support my logic but this is my observation and I am satisfied with my conclusions.

r