Letting off the gas will engage the engine brake. This will be very noticeable when going down a hill. It will make a bit of noise. I haven't taken the CVTech primary clutch apart yet, but some have a "cog" in them. The pulley will turn a bit before the slack between the cog and pulley are taken up and make a clunk type of noise. Can-Am uses this type and the first time I heard it, I thought something was wrong. Get on a 1000cc ATV and it is a very loud crack or clunk you hear when you get going or let off the gas and then back on it. Not sure if this is it, but worth noting. Rear brake noise might be junk on the rotor or too hard of a pad on there and it might not be bitting in and just slipping