Ok i have to say that i had the same issue until this last weekend of racing. my brother and i both have the go tech 3 port sport motors and had lean bogging issues after a half of a tank. it was frustrating i changed to an os carb and my brother kept the origanal carb on his after trying to tune the motors a local guy we raced with who has the same 3 port sport motor showed us that once you set the low end to a 3 to 6 second pinch test all you have to do from there is tune the hsn. I have to say once we both did this we had all the power we needed and the low end bog was gone and kept a consistent tune throughout the entire race from then on. so from my experience set the low end and then tune with the hsn.

worked for me and my bro hope this helps any one else having the issue as well