P51: My YS110 with APC 16X6 and pitts muffler turns around 9600-10,000 depending on the day and my tuning abilities. In this forum there is a thread called "YS Owner's Club" which has really great information on the 110. Also, if you ever need it, Dave Shadel is a YS Expert giving advice in the YS manufacturer's forum under the glow engine sections.