The truth is that if you here 'KoK' sound when engaging a gear, high percentage of that particular gear piece going to koyak soon..if not already koyak.
Ie, if u engage 2nd gear, and 'Kok'...then 2nd gear koyak soon lor. If you accelerate and it 'Kok', then maybe u want to check if your anti-roll bar joint is properly tighten or the bearing loose out (have to replace). Depends on where the sound comes from (front or rear roll bar).
The last possibility is using twin plate clutch or a set of good racing clutch. When engage, (change gear and release clutch), the grip is so bloody good that u can hear the 'KoK' sound..damn freaking loud like the entire drive shaft falling off. Anyone using HKS GD Max or Pro Twin Plate can second this statement lor..I am one of the 'victim' of this HKS conspiracy ! hehe