Air intake

Is it true that chips that connect to the maf/iat sender do nothing for performance on a 5.3 2011 silverado?

pretty much... the maf measures the air going into the engine. It is over written by the O2 sensor reading the exhaust. If the O2 sensor reads too rich it will change the fuel trim to make it leaner and if it reads too lean it will richen it up. That's what fuel trims ( long term and short term) are for. So, if the change in the maf sensor is too much you will end up setting a code for too lean or too rich.

How can you get more horsepower out of a stock computer on a 5.3 2011 siverado if not by one of those chips?