Since it was inexpensive, I ordered the air tube/throttle body spacer kit for my STOCK 06 TJ from Rusty's Off-Road. All it is is a TB spacer, a piece of hardware to reposition your stock air tube, and a K & N filter. I'm not saying it's a miracle worker, but amid all the intake bashing, for around $120 I saw a slight improvement in MPG and a slight increase in 'pep', especially when pulling the RPM's out of the basement in 2nd-4th gears. Maybe it's because I'm pretty much bone stock right now, but the money spent is justified by the albeit slight but noticeable increase. Just my two cents.