For me, with Madstad 13", Gull Wing Roof, and Rear Deflector, I get almost no air in the cab. I also have the front side fenders removed plus the DDM Hood Vents, but that was after the above. Truthfully, I have found some times that I put my hand out to the side to get some air.
How far up/down do you have your Madstad adjusted? I keep mine about 1" above the dash to allow some air to come through underneath the windshield. It creates an air bubble in the cab (similar to a pickup truck) that forces the air up and over. I can even wear a ball cap with no issues.