""If I had to pick a specific rpm I would say above 3500-4000.""

From what I have tested, that is the range for the HSAB's. The last two jet changes that I made, I went leaner by 2 sizes and my 3500/4000rpm range only leaned out by .2 each time. Not allot of A/F change for 2 sizes and my lower rpm range can't go any leaner. So this rpm range is where I need to lean mine out while you are trying to go richer.
I need some small drill bits in the .045-.050" range for my next HSAB test. What size are you going to test?