do they work how much better gas mileage do people get ? Also has anyone tried that little fan thing that goes into an existing Jeep grands air intake pipes.

Don`t waste your money, none of that crap works!

x2 they dont. Its a jeep. Theres no such thing as good gas mileage

I beg to differ. I just installed a new K&N FIPK and an Air Raid TB Spacer. I'm not going to make any wild claims of 60mpg, but I have noticed that i'm not filling up as often, despite driving more. I also have more power now. I don't have to drop out of OD to go up a hill on the freeway. I would definatly recomend both of those products. Unless it's a turbo or supercharger, don't put any fan in your intake system. All that will do is add turbulence, which is what you're trying to get rid of in the first place.

Hope you decide to make some changes. These took me an hour, and now has me hooked.

Good luck!

Bryan