Yeah there are no aftermarket under the hood upgrades available for the CX-9. Kinda sucks. I have a backup airbox (I have 2 airboxes) and one is swissed cheesed with a k&n. It is so loud I couldn't stand it anymore driving around with the family. So I put the factory box back in, with K&N filter, and just took out the snorkel on the side.