For many import/tuner enthusiasts, how their baby sounds is just as important as how she looks and performs—whether on the street or on the track. That sound and performance share a common bond, and you happen to be sitting right on top of it—the exhaust system. If you’re still using a stock car exhaust system—muffler and catalytic converter—you’re sacrificing engine horsepower and the sheer, unbridled pleasure of hearing your import/tuner’s true expression. And if you’re considering achieving an engine horsepower increase by flaunting the law and going catless, or have already gone down that road, read on for why not running a cat on your exhaust system isn’t the best route to choose, in addition to it being illegal and costly.
Stock mufflers are designed to absorb sound. With all their twists and turns, they get the job of dampening the noise done, but in doing so, they’re the most restrictive component of the car exhaust system. That air-flow restriction is robbing you of engine horsepower and your vehicle’s natural sounds. So if you’re looking to improve engine horsepower and harmonics—without going broke—your first consideration should be to replace 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 you have to have one, if you want to avoid big fines and possible impoundment.
So, what’s an enthusiast to do? Replace that stock cat with a high-performance one. ImportTuner magazine featured a great study that shows how they netted an extra five horsepower from their ’99 Civic SI, simply by moving from a stock cat to a metallic core Magnaflow OBDII cat. While a ceramic core might be cheaper, it delivered slightly less of an increase in the test. 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, that same dyno test showed only a one-horse increase as compared to running with a cat—hardly worth it, given the risks and considerable cost of running afoul of the law.
If you’re still running a stock exhaust system, sounding better and staying legal is easier than you think, and who doesn’t want that?
Editor’s note: Your new, robust sound and increased horsepower are bound to turn a few heads. Switching exhaust systems is easy with quality auto parts from Advance Auto Parts. Buy online, pick up in store.