Its a balance thing. There are a few differing opinions on this. If the engine is too far back, then it is nose light, typically some down plate counteracts that, but for speed you don't want the drag of the plate. If everything can be in balance, then nothing fights anything else, and top speed and stability are happy. There are many ways to skin this cat and many will work close enough that the speeds are close. Ride,stability and safety are another story. TIMINATOR
