If you didn't have any major restriction from you stock filter, expect nothing.

People often have unreasonable expectations of a filter change. It really won't do anything unless it was restricting air flow. It should never do ANYTHING for low end torque -- air flow just isn't the limiting factor.

The biggest gain you're going to get with this filter is a much cleaner engine. Better mileage is HIGHLY unlikely due to a free flowing filter.

 

John is right, the advantages are MUCH cleaner air and MUCH longer service life than a regular filter. Although the service life is a bit shorter than what K&N --CLAIMS--, the amsoil filter is MUCH easier to clean (vaccuum or blow it out), and does not have any oil to gum up the intake track.