@pittsburghracer , have you ever checked the gains of just the “pinch” after everything else? I believe you did in a different thread. If I remember correctly it was 5 CFM.
I’m pretty sure I did in the part I or part 2 in the Speedmaster sticky post. Honestly the head bolt bulge removal does more as it allows more access to the short side and better shaping. But one compliments the other. That why I port to the pushrod tube first then it opens up more area to jump on the bolt bulge next. The worst part of the whole job is shaping the short side. I have a couple dimensions I want to hit before I even start that job or it will be coming off the flowbench and back on my porting bench. I wish I could give out those measurements but that would be a whole chapter and guys would be more confused after reading it.