One certain difference with a K&N is that more dirt gets in your cylinders. The Web is full of K&N "performance" discussions with the jist of it being that stock engine filters have more than sufficient air flow (CFM) figures while race motors that get rebuilt every season or sooner may benefit from a higher flowing air filter.
Added expense and maintenance needed to clean and oil the K&N doesn't seem worth it...I was a past user on tuned HiPro motors with data monitoring and never saw any real difference in HP/Torque...just "IMHO" as they say.
Originally Posted by zztopgun
My GC has the hemi and I'd like to put a k&n filter in it to increase sound and performance but wasn't sure if it makes a worthwhile difference with this engine. I was hoping to get some feedback before I spent the money.