I never used to use the rain sock, either while riding in the rain, or when washing the bike. I kind of like the CVO 110 emblem on the air cleaner. The rain sock just makes it look like any old aftermarket part, and call me shallow, but I like people to see that 110 on the side. Anyway, we got caught in a very heavy rain a couple of months ago, and the bike coughed so bad I thought it was going to die. Since then, the rain sock has been on it all the time. I have found that it does not seem to restrict air flow, and acts as a pre-filter to keep bugs and dirt out which keeps the filter cleaner longer.