I am thinking about getting a Throttle body spacer for my 04 Frontier 3.3L, but is it worth the hundered bucks? Hows the power increase and does it do anything for fuel mileage? What about a cold air intake? Do they improve mileage at all? I have a Gibson catback and it seems to have freed up some power, and just wondering what else i could do to it to get some more miles per gallon and power.