How about running 30% in a Super Tigre GS-40? I was lead into this by a well seasoned flyer. The 40 runs strong but, it sounds like it's under water (if that makes sense). The other 2 strokes at the field have an even buzz sound. My kinda bubbles? I do have it running rich. I thought I'd try and lean it out some and it quit running on a throttle up after a touch and go. So, I riched it up again. I was going to try the 10% or 15% the next trip out. Just see. I just started flying my second plane. It's a Big Stick with an OS FS 90. That runs "sweet" on the 30%.