Isn't proper exhaust manifold design supposed to give priority to the wastegate, not make the exhaust gas have to make a complete 90 degree turn before exiting the gate(s)? If you gave the wastegate priority you would not need 2 44mm's to control boost. I have seen plenty of properly designed manifolds make upwards of 800+whp on a single 44mm TiAl, something similar to this:
I know you seem to have time constraints in getting this kit finished finally, but this would save your customers time and money in the long run. Installation and pulling the gates off off this setup will be a royal pain in the butt. I feel bad for the mechanic who has to install this thing.