How do Exhaust systems Increase Horsepower?

How  pretty to  Increase Horsepower With  too a  Flowmaster. Many vehicle owners  slowly have  turned  pretty to  Flowmaster in behalf of aftermarket exhaust systems designed  pretty to   restlessly increase  torque and h. p..

Does Dual Exhaust Increase Horsepower?. ... Dual exhaust definitely increases the h. p. of  too a  vehicle, and they do without such that on the  unconsciously part  of