Ok so here it is my mileage has shit the bed i havent used a full tank yet and im at 100miles at half tank...the plugs, wires, cap, and rotor are all new....my only concern could be the air filter (which made me buy a cold air intake woohoo ...clogged cat, or a busted o2 sensor....whatcha guys think? could the air filter be that big of a decrease in mileage, i was really just looking for a reason to buy a cold air haha!...post back