That does look great... I have to say that's one of the nicest A/C's I've seen.
My guess is that there is "some" opening on the back side that allows air to be sucked in not only from the front. Where I'm going with this is that motorcycle air cleaners are meant to be side mounted, not forward mounted.
You can see from this picture of my last Willys streetrod that my air cleaner also faced forward. But when rain came around I had to put a "sock" over the front inlet and just let air get sucked up from the openings on the bottom of the air scoop.
Just as a warning, I would get a nicely fit "sock" cover that you can slide over the front when you're driving in the rain.
Even my '09 CVO Harley with an exposed A/C, Harley sent a waterproof sock to cover the element when riding in the rain. This sock lets air through, but not water.
What happens is that the element will get saturated with water and choke out the motor. So just be prepared for the rain.
