Looks like after break-in your 15x6 RPM went up 2,000 RPM.
Speedster 1919,
No. 7000 rpm was the rich 2 cycle full throttle and not the max rpm. I was getting about 9000 rpm to begin with. That's why I'm a bit concerned. However, I can say the mid range and the idle definitely improved. The engine runs very smoothly from idle to the top, except at idle, it kind of 4 cycles, but didn't seem to die when a sudden full throttle was applied. I did various transitions many times and they all sounded great.
I have 2 ST GS-40s and both of them give more than 1.2 HP, although the rated HP is 1.15 HP. I did use 10% OMEGA but that's not high nitro content. So that's where my expectation comes from.
Ken