Yeah, you can gut the factory air box so you get flow to the panel filter.

The actual restriction is the accordian tube from the airbox to the TB, not the box itself. K&N/Spectre/AMSOil Dry-flow...all those drop-in's would work just fine. I'd also recommend a PowerLog front manny too. Super easy install, and gets rid of that awfully cast piece...

ZZPerformance - 304 Stainless Power Log #ZZ-304PLOG