I think Dad was getting 10,000-10,500 on the ground with the BCM Pitts and 15% nitro. I only have 3 tanks through mine with a 15x7 and 10% nitro, and I haven't tached it yet, but I am hoping for 9000-9500 with the stock muffler. The 15x7 unloads a bit in the air, but probably because its not yet broken in completley. we will see once I jump the nitro from 10 to 15% and go down to 16% oil from 18. Plan to fly it again tomorrow and will grab a new battery for the tach before I go. Stay posted!