I have Naca ducts on mine (worthless), and Snap Vents. If I did it again I would
only install the Snap Vents. They can go anywhere from hurricane in the cabin
to closed.
The only other mod I might make is to tint the overhead, since Kitfox is another
word for "Greenhouse".
A crack free install method, but messy, is to use a dremel with sanding drums.
Which is very safe for avoiding cracks. Just mark a circle, and use cutter
wheels and sanding drums and work your way to the line.
Jeff