Watch out for any air leaks around intake hose!I developed one with out noticing,( caused motor to run to lean) it cost me a cylinder,piston and ring. I replaced all at begening of this week .Minus - kooso boost bottle.Have average speed of 38 mph. same as with the bottle.I will sell kooso boost bottle for $10.00 plus shipping if any one is interested. I payed $50.00.Comes with chrome bottle, blue tubing, and intake adapter.Ive been running it on a 47cc engine with walbro carb. It will help for cleaner reving and a little more pull on the hills.