From what I've read about plausible improvements, I Understand improvement may be !% or 2% . Is it worth it? I think u can feel the different, when u use it specially with 91 unleaded. interesting... anywho, cost saving is the main reason i purchased it. $80 for my 02 gen 4.5 camry, and better built than those oem tissue paper crap. at high revs the engine is a lot louder as you would get from installing a pod filter, though not that extreme. in terms of feeling the difference, i dont feel any, just sounds louder. not after a performance boost, but for me it will cost the same as purchasing 2 to 3 stock oem air filters over the lifetime of the car, so why not just get the better one? youre also helping the environment too AHAHA louder interesting...... I thought it only happen on high performance intake kits. In my case, the ACR40 ECU will adjust the setting based on the car condition and day-to-day driving.