spudboy: replace your downpipe and turbo elbow with a downpipe with the elbow integrated into it. the stock elbow is quite restrictive and maybe what is hindering you.
a divorced wastegate is referring to the downpipe. basicly it splits the wg and exhaust flow to allow a smoother flow. in stock form the flow is quite turbulent.
look here to see a divorced down pipe
also if you have a standalone, why even use a afm? that is limiting you're airflow. and you're tuner said the stockers are adequet? for what? what are your goals? try replacing your downpipe and see if that fixes your boost problem, it will also net you a few ponies and spool your turbo quicker