I replaced the chain and sprockets as the old onces were thoroughly worn out. Took the bike for a ride up in the mountins and couldn't believe the difference! The bike now runs sooooo smooth. I did back out the mixture screws 1/4 of a turn extra each and it just runs brilliantly. So it's a new OEM filter, new plugs, checked and adjusted the TPS, carbs balanced, jets are standard but mixture screws set to 3 and 3/4 out from lightly seated. So far I'm really happy with the power and the fact it's runnig so well I'm now less inclined to mess too much more with it..... unless someone can vouch for the difference I can expect from fitting one of Holeshots stage 1 kits? Love my B12!