Figured just as much. Ive got some rubbing compound and some rough waxes I'll try. If they dont work, I'll try a claybar.
I will say though, I notice a difference with it off. The visor lifts the jump-off point for the airflow, thus helping the air flow right over the open roof as opposed to coming into the vehicle.
Just this morning I had it open, without the visor and I could feel the air rushing in at my head. Im not used to that, lol. That may or may not be something I put back on. Or, Ive seen ones that are much smaller and a lot more lo-pro. Almost look like an M3 spoiler for your sunroof, lol. But they're all more than likely stick on.