I use an APC 15.75 x 11 APC 3 blade prop. It starts life as an APC 15.75 x 13 prop that Dave Lockhart re-pitches to an 11 pitch. On 20/18 S&W I typically see 7700 to 7800 rpm at take off. Unlimited vertical with my 10lb 7ounce EMC2, very, very slow down lines and nice relaxed flying pace. Pipe is an ESD2C140S9 from Central Hobbies. Header is Macs 2 1/4" rise run at full length and about 3/8" between the end of the header and the neck of the pipe.
Ed M.