pdargen, The HD "Compact" filter is about 1/4" from the lower. The glove box really becomes useless at this point. If I want to put speakers or use the glove box for storage, I will go the route of Wachuko's bike.
+1 - After seeing a few photos from folks here (foyboy) and the feedback... going with a shorter filter would have been a waste of $. First, you loose the cool black and polished cover. And second, the glove box is useless as you can't open the thing to get out squat, plus, if you ever install speakers, the short filter will not work anyway.
My suggestion is to spend the money on a new setup. Many to select from. From the stock unit found on the Street Glide CVO to the aftermarket.
This is what I went with... but thinking about changing the face for the new Clarity line... along with their Clarity derby cover.