I have a 73mm C&L right now, I've heard horror stories, so I decided to change it. I am also going to get some Accel plug wires, if I can't find any FRPP wires soon.
I had one on mine & it ran so lean it was off the chart, dropped in a pro-m & it made a major difference, still lean but atleast in a semi safe range, same thing the dyno shop told me but I still have my lean problem I'm trying to troubleshoot but pro-m did help "alot" and pro0m make a optimiser so you don't have to recalibrate & you can adjust air/fuel rations etc.