Why is it that the stock plugs and the plugs for screaming eagle heads have different thread size and been trying to find info on my S.E. heads any help out there ? And what is the big thing about S.E. heads 97 Softail Custom Bought the bike as is 10.5-1 forged pistols EV 46 Andrews cam S.E.select curve race ing.mod. S&S super E jetted C.M. adj. Push rods HD clutch w/18 degree ball ramp last bike I had was 76 XLCH CHOPPED AND RAKED that was 85 when I had to sell it personal reasons got the 97 in 13 work on my own **** can't see paying for something I can do.!