Therein lies your solution as to "why doesn't it make more power" with it on.
Ask Santa for a cam ground in this century. One that has a lobe separation that is more boost friendly.
That cam has a 110 degree lobe angle. Typical power adder cams go somewhere in the 112-114 maybe even higher.
Consult the great @84Ttop. He should be able to add some insight on what cam profile would be happier having air forced past the valves.