MPG increase modifications
 

Which modification works best to increase MPG?...KN filter; KN air intake; performance chip; performance exhaust?The ammount of time it takes to pay for the mods with what you save in gas is a big factor.
Would differnet wheels/tires be worth considering?
Would a topperimprove aerodynamics and make a dif?
Woulda performance chip or the KN filter be hard on the engine?
Which make truck wouldgive the better MPG after mods?

Thanks in advance!