I've a 2009 & have read a bit about improving airflow with an airbox & filter mod, but am not sure whats involved or whether there'll be a big benefit? I've MIVV Suono cans, so no restrictions there, & its UK bike, so no exhaust cat.
My dealer I felt was pretty honest. I did an Arrow slip on, ecu reflash with eliminated the butterfly in the header, and keeps it open. When I asked Bout the air box mod or filter, they replied that they found the stock airbox flowed more than enough air. They said the best addition would be a k&n filter and leave the box stock. This is from a dealer that has dynoed several 1100's.
Mine 2012 1100 EVO.