Some people fit heavy duty springs if their clutch is slipping. Although clutch slip is more commonly the result of the putting in the wrong oil, putting too much oil in, the clutch being worn or the mechanism or cable need adjusting.
I fitted heavy duty springs to mine before I new all of the above. Although my clutch was slipping because the OEM springs were 17yrs old and with continual use and thermal cycling had shortened. At the time I wish I'd just fitted NEW OEM springs, although I've actually got used to having a heavier clutch now.
I think new springs are relatively inexpensive compared to the cost of clutch plates.
