Will changing a stock ford muffler to a flowmaster 40 mess up the engine computers?

the stock muffler has the exhaust from two manifolds going into it, the stock muffler is quite larger than the flowmaster and im wondering if the size differance will screw up the trucks computers/engine.|||If you're doing a cat back exhaust no it won't mess anything up. I still recommend unhooking the negative side of the battery though. really the only time you need to worry about the computer is if you have to unhook the O2 sensors if say you were doing aftermarket cats.|||no it will not and u should notice more power