sound governor??

My 2006 Saturn Vue will not get loud. Is there some sort of governor/limiter thak is supposed to protect the stereo system? How do I disable it? I do not want to buy a new head unit, because it is my company car.

I believe the GM vehicles have that in the head unit to try and stop distortion...I may be wrong

I've got an 04 trailblazer and it's the same way.