Jordan:

Not a toss-up at all. If you want to go fast, the K&B 48 is the better choice. It's not happy swinging a large prop. If you have an application wanting torque more than speed stay with K&B, but get either the Sportster for highest torque, or the model 4070 for an engine in between the characteristics of the other two.

If you just like the OS style, save a bunch of money and get the Magnum XLS 52. A better engine than the OS also. The Magnum is a genuine ABC engine, the OS uses the cheaper nickel plating. And charges 60% more for it, too.

Bill.