Also note, that improved economy is more about the torque then the peak BHP. (so it will make more difference when your car is loaded)
Torque is relates to the ability to carry load whereas BHP refers to the acceleration or speed.
Think of a skinny fast guy and a strong slow guy,
the fast guy can run with a cement on his shoulder but only one, but the strong guy will carry 2-3 bags in one go.
So more torque means that quite often you will be able to just
accelerate in 3rd, 4th or 5th without having to change down.
also makes for an easier drive.
Its worth shopping around for your tuner, a good one will talor the power to suit your demands ie lots of power low down, or more top end, and try and iron out the flat spot that comes due to mechanical reasons @ a little over 3000rpm.