Probably bladed bars is the way to go. Shame that you cannot get aftermarket bars that would be bolt on for the Escos. they make massive difference on SUbaru and Mitsubishi, and Escos seems to be out of balance with 28mm bar in front and 22mm (?) one in the rear. On jap cars have experimented with dozen different setups and same diameter or even slightly thicker bar on ter rear with the rear beeing adjustable seems to work nicely on road cars with some track-day capability.
Anyways - what would you do on my car apart from rear beam? Two things I cannot get used to is not much feel through the steering - I am wondering maybe steering rack mounts? although I have brand new rack with new mounts and the rear end not feeling properly attached to the chassis - maybe new beam should be solid mounted (I have it polybushed)?