Just my two pence here mate. I have the os vzb and bought it brand new. Lovely engine, very easy to tune, also have been advised by the guys at bmm racing to change the conrod for the uprated one thats on the higher spec os engine after a couple gallons so I did and it flys. Also the fastrax enduro is a wonderfull engine. My brother runs it and for the price it gives you everything you need to race and has great power for what it is.