Because I'd rather have the bigger intake. The exhaust will take care of itself. And it's almost impossible to test exhaust ports on the flow bench.
When when the weather warms up I'm going to measure the W-2's I have and see if I can fit a 1.500 exhaust in there and still get a valve job on it. If I can fit it, I will.
These heads have way too much exhaust valve and port area.