That engine will run well up to 19,000 but I wouldn't go much above that as the crankshafts use to break on those front intake engines at really high RPM (22,000). You might have to shorten that header to get the peak performance up at a higher RPM, it looks about right for the 10 x 6 you've got but that pipe isn't the best for 15,000 RPM. We ran that motor in our Calzona Q500 class for years, mostly set up by Clarence Lee and hopped up by Mike Del Ponte, and the RevUp 9 x 7 was popular but you had to thin it out a bit and many were twisting in more pitch to get 9 x 7.5 or so.

For better speed, you'll need more pitch, say an 8 x 8 or so, but you'll have to try a few different props to see what works best for that airplane, and again, I wouldn't spin it up too high for a sport setup as you'll only shorten the life of the engine.

Drew