I ran a 14~8 APC on my S90K with a Magic Muffler at 10,000 or so rpm. Pulled an (8.2 pounds dry) Joss Stik with authority. Including straight up.

Terry in LP

edit for adding: Yeah. I built my own landing gear as part of the weight saving effort. Made it out of piano wire front and rear pieces wrapped and soldered together just above the 'axle bend'. Came out quite a bit lighter than the stock f/g gear. Taller too.