you are the only one going round and round you asked why we answered. i thought i gave you a very thorough answer as to why the vtec system is different on the k24 accord/crv motors. i forgot about the 25 degree VTC limit on the tsx motor. the stock pistons might hit the valves with more VTC from the factory. i think the k20a2 head does flow a bit more anyway.
all in all its cheaper to just build a k24/k20 than buy a TSX motor + k20 cam gear and build. also you have to consider a lot of people have a stock k20 swap in the car before they build a k24/k20 so they already have a k20 head and can pick up a block for cheap 400-600 and build.