I have checked into MD laws and they limit tint to 35% on front side windows. Rear windows and sunroofs can have whatever the owner wants. There is also no allowance for tinting the front windshield, but the only time I heard of this being enforced was when a local kid thought it would be cool to put an opaque white tint on the upper half of his windshield. This lasted about a week before he was pulled over.
I am also looking to get tinted somewhere that will do a high quality job and give me documentation that I can show to LLE if I'm pulled over.