Your local dealer likely has one in stock. I think MidAmericaPowersports would be closest to you. Otherwise the TwinAir part number is 158046 for the 2011 bikes.
You can confirm that here:
https://www.twinair.com/applications...g.php?s=158046
Searching that part number brings up multiple listings all over the place including Amazon and Ebay.
Matto's would be able to get it for you as well..