I'm coming up on 18k on my 06' 636 and its time for the clutch to get a new life line. Would up grading to a Kevlar set up be overkill? I'm doing 5-8 track days a year on top of occasional street riding.:doh:
I've done a ton of trackdays on the stock clutch without a problem (over 80??). Certainly how you use the clutch would play a factor, but I can't see a good reason to justify an aftermarket clutch on the '06 636 if you are doing only 5-8 trackdays a year.
I put a Barnetts Kevlar clutch set in my '04 636 and the only negative is that initially it is TIGHT! Specs are spot on but the friction is a bit higher than the stock clutch. Took a while for it to wear a little, especially since I use synthetic. If I ever need another I'll use the stock discs and plates.
With clutches, stock is usually the best. If you want stiffer springs then aftermarket is a good choice but for drive and driven plates I would always stick with stock.
I had to adjust the clutch cables on my 636 a few times with only 8k on it. Seriously, check the cables down by the clutch cover, there's a little adjuster thingy down there that can get out of whack.
69 track days and still going strong, Oh add 3 race weekends to that. The stock clutch is great! Whenever this one needs to be replaced, I'll get another stock one!