What to do 07 chevy?

i have a 07 1500 chevy Z71 pkg but no 4WD (anti siked) V8 4 door LT i ask the if i can put a chip on it but it will void the warrnty i have no idea how to put hp or mpg on it. only haves 7,000 miles on it im getting a black grill gaurd on it and black step sides. im also thinking putting air intake but i have no idea what kind, K&N air filter please help me