stick with stocks unless you'd like to have your engine suck in all kinds of junk particles.. K&N lets in bigger particles and thats how it "improves flow". I'd get a ebay cone filter with a pipe for 15-20 bucks and call it done. (search wrangler intake) I had K&N and switched to custom intake and had some difference so K&N panel filter wouldnt have done much difference.
well my jeep came with the k&n from the dealer so i cannot tell you any difference from the stock panel but i did however install a custom intake system on mine and bored the bottom of the throttle body since it gets smaller for some reason .. the intake gave me a little gas improvement.. 2ish mpg and it pulls stronger in the highs (keep in mind driving it like a maniac and flooring it on every stop light would worsen your mpg more than stock because you get some more air).. The throttle body was where i got noticable power increase and would recomend it. I cannot tell you for mpg since i just bored it couple of days ago and have used up less than a 1/4th tank but it definetly pulls harder and it makes a whisling noise when you step on it. Quadratec has bored throttle bodies also ~200 bucks and i did mine for free and it was easy.. pics in my sig
I also would avoid the K&N for the same well-known reasons Triple88a said. Besides, other than perhaps a placebo effect, it won't help the performance of a TJ engine. A K&N can help the performance of some other car engines that have a restrictive air intake system but the TJ's air intake was specifically designed to be non-restrictive. Neither will it help with fuel economy in the least. I woud stick with a conventional paper element air filter if it were me.
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