That was my first impression too. But w/the muffler pressure line attached, I tweaked the HS needle for about 150-200 RPM less than peak. I guess I convinced myself that a sustained 900 RPM difference wasn't it, especially since the change in RPMs was almost instantaneous. (Not like pinching the line and seeing a gradual RPM increase.) I'll experiment with leaning it out a little more to see if that is what it was. I learn something new every day. THANKS!

Dave