Thanks all. Were the original K series Superlights delivered with 3.9 or 3.6 diff ratio? Paul, I was considering this and your comments have started me thinking again... but I think 6 speed and 3.6 is ideally what I want: Closer ratios than the 5 speed but cruising speed somewhere between standard 5 speed and 6 speed with 3.9 diff. Roughly how much would SPC/BGH charge to change 1st and 2nd gears for ones of a higher ratio? Sam, thanks for this. I will consider this option and drop you a line. How much difference is there between the Supersport and 633 cams? If I could get some used Supersport cams, would these be worth considering or is it worth the additional outlay for some 633s? James