who makes performance upgrades for the 95 GTP with the 3.4 dohc engine?

i want to supercharge this engine and change from the weak 4spd auto to a 5 spd or an upgraded auto trans.
i understand that the 3.4 dohc motor is a pain to work on and expensive to maintain, but the only other option for me is to swap out the motor to a supercharged 3.8.
There seems to be no aftermarket support for the 3.4 motor.
my GTP has only 54000 miles so the engine should still be in fairly good shape.
Anyone who can steer me in the right direction, I would appreciate it very much.