Looking for what air intake will increase my
horsepower the highest? Where should I buy from?
I have a 2016 Chevy Silverado 1500
You are not get much horsepower gain by changing cold air intake by itself, I doubt you will even feel any differance, even the flow charts show the increase is not that great, a computer reprogrammer is the best way to gain power and performance if your not wanting too tear into the engine. And your rig is most likely still under warranty, so don't do anything that will invalidate that.
K&N makes some of the best cold air intakes, but as tennisshoes said, gains will only be slight.