The factory horsepower rating for a 2003 5.7L Hemi is
345 hp. A cold air intake will *increase* horsepower slightly, but there's no single definitive number. The gain is typically in the range of
5-15 horsepower, depending on the quality of the intake, the rest of the engine's modifications (if any), and the testing methodology.
Therefore, a 2003 5.7 Hemi with a cold air intake might produce anywhere from 350 to 360 hp, but it's impossible to give a more precise figure without knowing the specifics of the intake and any other modifications.
