I'm not sure you're going to gain .03 just from switching from one graphite to another. My opinion is, you would be better off to perfect your graphite process overall, not just the actual graphite.
That said, our fastest cars have always run Derby Dad graphite. Definitely use whatever is the fastest, but I don't think it's the be-all, end-all of solutions.
What you do to the wheel bore and the axles before whatever kind of lube you put on matters... A lot