I've bought a GS500F and know it needs a new chain. My question is, should I replace the sprockets as well? I'm pretty good with tools and love to have a go but want to know how important it is to use a torque wrench to secure the sprockets? Also, i've been searching around for info on what kind of chain to get but cannot find the info I'm after. Are there any brands or specific types I should avoid all together? My rear sprocket has 20,000kms on it.