I'm at the same question but here is my best answer. Royal precision says 5.0 is a regular. 5.5 is a stiff etc. if u go to a 5.5 project x 95 shaft flighted this will be a regular some say reg + (firm) and 6.0 would be stiff. as for a kbs tour 90 reg would a reg + I choose the 5.5 x 95 over kbs. I played royal precision 5.0 in my mp 52 and loved them. my swing speed is 73-80 mph. lofts and shaft length have a lot to do with distance per club from different makers.