That's definitely the stock air box that came on the bike, and is relatively restrictive with regards to air flow into the motor. There are at least a dozen or so alternate intake systems out there. I can't find the thread right now, but there used to be a thread on this site that had all the parts needed to "Roll your own" Screamin' Eagle air filter system, the basic components of which were the chome backplate, K&N air filter, O rings, etc. Others are Arlen Ness, Zippers, Doherty, just to name a few. As has been mentioned, you'd probably be ahead of the game if you checked the intake system for leaks, made sure the injectors are clean, etc. In the process, put the better air filter kit on, then proceed with some kind of tuning device. As mentioned previously, the Power Comander III would work well on this year model bike, and most tuners are familiar with that device.
Jerry (grc) was the member who originally had the thread about the "roll your own" intake...perhaps he will see this, or you could PM him and he could give you the parts list to order from your local HD shop, and you can get the K&N filter on line in a number of places. I originally had this, and some slip ons on my '06 SEUC and was happy with the results with the HD ECM download available at the time. I later went to Rinehart True Duals, so put a PCIII on the bike and got it tuned locally. Ran like a top.