And so starts the classic 2 stroke vs 4 stroke power to weight ratio debate. My money is still on 2 strokes for performance where maximum power to weight ratio is needed. Yes, I'd be the 1st to admit that 4 strokes have really come a long ways and in some cases (new Saito 1.00 and the Y.S. engines) they've almost closed the gap power wise. If you like your O.S. .46 FX, try an Irvine .53 - you won't be sorry!