In general, a quality set of headers should provide an increase of approximately 10-20 horsepower, and if you're restrained with your right foot, you may even see an increase in fuel mileage.

Do headers give you HP?

Headers Do Add Power, But The Increase Depends On Your Engine. ... You know, the ones that claim, “Just bolt this part on and its worth 30 hp.” After adding up all the claims, Bobby exclaims, “Hey, if I crank up all these parts, my motor'll make 500 hp—eeeeeaazy...” The only problem is, power claims can be very elusive.

Do headers increase performance?

Headers are one of the easiest bolt-on accessories you can use to improve an engine's performance. The goal of headers is to make it easier for the engine to push exhaust gases out of the cylinders. ... The gasoline in the cylinder burns and expands during this stroke, generating power.