Vintage Duff.........The .46 motor is a great basher motor if you break it in properly!! The .46 motors tend to take longer to break in than a 21, so you must be patient with your breakin process. Figure on 10-15 tanks of fuel before your .46 is completly broken-in. A person on another website put a .46 in his offroad dune buggy and is smoking everyone at his track! The Cen .46 seems to have one problem and that is rear bearing failure I would reccomend replacing the bearing in the motor with Boca Bearings.