​​Tuner Notes: Why Replace an Exhaust System

A Thrush muffler with cutouts For many import and tuner enthusiasts, how your car sounds can be as important as how it looks and performs. Sound and performance share a common bond—the exhaust system—and there are some pitfalls to keeping the stock exhaust system. Those car exhaust systems, consisting of a muffler and catalytic converter, sacrifice engine horsepower. You'll also miss out on hearing an import/tuner’s true expression.

Why replacing a stock car exhaust system is a good idea

Stock mufflers are designed to absorb sound. (Learn more about the different types of mufflers.) With all their twists and turns, they get the job done of dampening the noise. That air-flow restriction, however, robs the engine of horsepower and a vehicle of its natural sound. To improve engine horsepower and harmonics—without breaking the bank—consider replacing the stock car exhaust system with a performance exhaust system (the muffler and catalytic converter).

Why replace the catalytic converter too

Second only to the muffler, a stock catalytic converter is a big engine horsepower thief—but necessary to avoid big fines and possible impoundment. So, what’s an enthusiast to do? Replace that stock cat with a high-performance one. While a ceramic core might be cheaper, it delivers slightly less of an increase. More worrisome for import/tuners, though, is its lower melting point and the resulting failure in high performance, or boosted applications. And, when it comes to removing the cat entirely, improvement is minimal and hardly worth it, given the risks and considerable cost of running afoul of the law. If you're looking for additional ways to improve performance without going broke, check out our article on three easy performance mods. Considering swapping out your stock exhaust system? Share your ideas in the comments.