probably like crap. lol. let me follow my train of thought... it wouldn't be able to get the extra air/fuel into the crankcase while the piston is up, and the vacuum would still be in the crankcase, so it would pull the exhaust into the crankcase, which may still be on fire, so it would probably ignite the air/fuel in your crankcase and turn it into a big combustion chamber. it wouldn't give u more power tho, lol.
but who knows? maybe you should try it! hahahahahahaha