The cat back portion of the exhaust system generally refers to the section back of the rear catalytic converter. This includes the resonator, rear exhaust pipe, muffler and tip.
The resonator’s main purpose is to attenuate the sound of high-pressure best ba xr6 turbo exhaust installed in the system. Sophisticated units are designed to internally reflect the sound waves so that they collide with one another and cancel out, deadening the noise significantly. It is possible to purchase units that will produce a low growl instead, though this is more for style purposes than practicality.
A muffler is designed to do a similar job to the resonator, albeit to a greater degree. The most basic muffler works on the absorption principle and uses materials such as fiberglass or steel wire to absorb much of the sound before the exhaust gases are expelled. Another common type of muffler works by restricting the flow of exhaust gases which drastically cuts down on noise.
However, this also reduces the efficiency of the exhaust system and ultimately the efficiency of the engine. Finally, more sophisticated mufflers work using the same reflection principles as the resonator combined with absorption materials. These are the best performing mufflers available and provide the greatest reduction in noise possible.