Back pressure robs your vehicle of power and economy. Reduced back pressure will cause immediate gains in both power and economy. If you modify your engine, for every 8-10% in power increase, you will gain 30% more back pressure, which virtually chokes the motor. This means that any modification at the engine makes a free flowing exhaust and muffler system mandatory.

There are three basic factors in noise control: Restriction, Absorption, and Reflection.

1. Restriction is best for reduction of noise, but worst for power and economy (as high as 16lbs of back pressure).
2. Absorption is effective when you pack materials such as fiberglass inside casing, but this is usually quite loud, especially when the packing burns out. Absorption doesn't control reversion.
3. Reflection, which is the most effective for power increase, is done with baffles and reflector plates with nothing to burn out.