I'll put it this way. You could dump the amount of money into your D16 that a B18C swap would cost, and still would not have much more HP than a stock B18C. You might even have less. Then you really don't have much room for improvement. Sure you could build a 300HP D16, but you could get a B18 swap and reach that output for a lot less $$$. It all depends on what your HP goal is.