How much horsepower gain from flowmaster exhaust on ford f150 truck?

You won't see a significant horsepower gain, maybe a few, from just installing a Flowmaster exhaust system on a Ford F-150. The gains are typically very minimal, often in the single-digit horsepower range, and sometimes even negligible depending on the engine and existing exhaust setup.

The main benefit of a Flowmaster exhaust is a change in exhaust tone (louder, deeper sound) and potentially a slight improvement in throttle response due to reduced backpressure. However, substantial horsepower increases require more extensive modifications like engine tuning, forced induction, or other performance parts.