Well broken in and flown OS .55AX on bench.
Weather, low 80's, very humid, just after 3 days of rain in NW Florida.
Fuel: Omega 10% Castor blend
Tach: Thunder Tiger mini-digital
Props: All APC
Muffler: Stock with baffle and Jett-Stream ordered for the 55AX
10-6 Stock: 15,700 Jett: 16,500 Gain: 800
11-5 Stock: 14,000 Jett: 15,000 Gain: 1,000
11-6 Stock: 12,800 Jett: 14,500 Gain: 1,700
11-7 Stock: 12,200 Jett: 13,700 Gain: 1,500

Comments:
1. Looks like the 55 isn't going to be a really high rpm engine
2. The Jett-Stream is supposed to be designed for the 11-6 and it gained a bunch on that prop.
3. I was surprised that the 11-7 gained that much.
4. Looks like high 12's to low 13's is the sweet spot on the ground.
5. I should probably go back and do some 12" props. A 12-5 might be right in the sweet spot