It would be better than your fourwheeler, really 400ex's are good bikes. You cant hardly break them. It will smoke a stock banshee pretty good, but not your ported banshee. If he ported it and polished it and put a 440 kit in it, then it have around 45-50 hp id say. A piped/hot cam stage 2 400ex will beat a stock banshee, so go figure.