Exhaust systems are car more complicated than they appear. At one point, simply dumping the engine's waste gases through a 2-foot-long 4-inch diameter sewer pipe was considered state of the art. Today, however, the end user can take advantage of the many enhancements and refinements of exhaust technology to create a system that is legal, exceptionally efficient and stealthy when it needs to be.
The Dream List
The ideal exhaust system would start with true equal length headers, utilizing a step-down design to eliminate exhaust gas reversion. These headers need not be of the full-length variety used by racers; on average, shorty headers deliver 98 percent of the performance of full headers without grinding on every speed bump in town.
For those requiring emissions compliance, MagnaFlow makes a series of excellent and efficient high-flow cats that rival a straight pipe for flow. "Sport Compact Car" magazine's test result showed a marginal 3 horsepower difference when it tested a straight pipe verses a high flow cat on a 350Z.
For those using dual exhaust, utilize an X-pipe crossover, such as those made by Edelbrock or Bassani. These crossovers balance exhaust system pressure, are proven power-makers and will give your car a more expensive and sophisticated exhaust note.
Phantom makes perhaps the best muffler in the world. Its electronic mufflers are as quiet as stock in normal usage, but can be switched to a full-loud, straight-through race muffler at the flip of a switch.
Shorter exhaust systems always flow better, so keep the pipe routing as straight and succinct as possible. Dumping exhaust in front of the rear axle and using a set of down-turns is the best option for practically any car, space permitting.
Use mandrel-bent tubing in your exhaust system. The added expense of this much smoother pipe pays significant dividends in flow, allowing the user to utilize smaller diameter tubing for more ground clearance.
Don't go insane with tubing diameter; 800-horsepower Can Am cars use 3-inch exhaust systems, so that should be plenty for your car.
Thicker, heavier tubing will yield a lower and more menacing exhaust note, since it helps to contain annoying high frequency sound waves on their way to the muffler. If you're dead-set on saving weight, place the muffler(s) as close to the engine as possible, and use lighter tubing from there back.
Titanium is the lightest material available and is used for just that reason on high-end race-cars. However, it is expensive, cracks easily and only sounds good on racers that spend all day at 8000 rpm.
Aluminum tubing offers many of the benefits of titanium, but at a much lower cost. Thin-wall aluminum is easily bent and can crack with heat, so avoid using it before the mufflers or on any weight-bearing portion of the system.
Stainless steel has always been the best option for most street cars. Though traditionally heavier than other options, modern race systems use thin wall chrome-molybdenum tubing to maintain durability while staying competitive with other materials where weight is concerned.
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