How much more horsepower will a flowmaster 60 series muffler give a vehicle?

the muffler is a flowmaster 60 delta, i am just wondering how much horsepower it will add to a car.|||hate to break your hopes. but just putting on mufflers wont increase your horsepower. it might even lessen your torque. more of a looks thing. if you want horsepower from mufflers. change out the whole exhaust system piping.|||if you are just having the muffler put on and no change on the pipe your gains will be minimal but there will be a small difference mostly its for the sound|||1 or 2