4cyl=smaller pistions=higher rpm=higher top end hp 2cyl=larger pistons=more midrange=flatter torque curve Not necessarily just i4s, I think 4cyl engines are better than twins for road racing. Look at moto gp, the two top bikes are i4 and a v4. Honda is supposed to be releasing a v4 literbike that is a step above the CBR1k. For street riding, even aggressive street riding, twins are better suited to my riding style. I spend most of my time in the midrage, so that's where I want power. I've never noticed my V2s or V4s being any more/less reliable than i4s I've owned.