From the factory, you had a cold air intake system already. The pretty add-ons are cold air in your wallet intakes, do very little if any to increase power, just make the intake side of things louder=more power obviously . The headers, doubtful they would really do a lot. You need to look at full length headers(which are not street legal on emission vehicles), or like on V8s, triple Y headers. Increasing throttlebody diameter can increase air flow and help top end power, but you end up with reduced intake velocities at lower rpms, robbing the engine of low end torque. That's the opposite of what you need! Now regearing, that will give you a performance increase, though costly for two axles. Driveline shops can do it, offroad shops(avoid tanner IMO), and a lot of independents can. The majority will want to use their parts partially to make their margin(hey they are in business to make money, not charity Obama work), and if you provide your own, expect a tail light warranty. Plenty of sources carry the gears, I'm sure jeepinbyal has them.