2008 Ultra with lowers with adjustable vent doors-- This summer before a road trip I took a 7/16 socket- removed-one bolt, 3 spacers and one ni-lock nut-- to remove the adjustable (vent) doors from my lowers to give the eng some extra cool-It took 2 minutes per side to remove them and I gained an additional 2 1/2 inches by 11 inches of air flow through the lowers on each side. That's equal to adding a 5 inch by 11 inch opening!!
Now, I've reduced the buffeting updraft by 75% around the tank , I believe it's because the lowers are acting like a wall of high pressure air (at speed). The high pressure air pressure builds in front of the lowers, and spills over the top and up around the fuel tank and into my face. By removing the little, rattling plastic sliding (vent) doors it released the wall of pressure and it directed it onto the engine, (my jeans wave like a flag behind the lowers now, even at 45 MPH).

I took a 4600mile treck thru 12 states in August, It was as hot as a boil on the devils a$$ for most of the trip, (10 days) The additional pressure/wind was channeled directly onto the engine as needed and not in my face. I opened the adjustable fairing wings for chest and arm cooling, (controllable). soon I will re-install the doors on the lowers for winter, but come next spring, off they come again...no need to remove the lowers. Next time you get a chance, check out how much more engine airflow your bike will have if you removed your vent doors, plus the added bonus of reduced updraft and buffeting.
Best to all:

R