It does not matter where the crossover pipe is positioned on the header. I go by my Kawi exhaust and it looks like they use a little bit less than half the diameter of the main pipe size. It is more the fast moving air is still in the header area, and once you slow that flow down, it is a reversion advantage for the other pipe about to fire off. So really, this is a grunt bottom end helper. If you are going for all out, then no crossover but all straight out the back end as quick, smooth with less turns as possible.

You have too tight a bend in the pipe, it could slow down the exit.