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Easy Exhaust Upgrade

Improving your car's sound & fury

Performance enthusiasts know that one of the best ways to increase horsepower—especially in computer-controlled vehicles—is with a less-restrictive exhaust system. Because any components downstream of the catalytic converter are legally fair game for modification, the automotive aftermarket has a cottage industry in so-called cat-back (muffler and tailpipe) exhaust systems. Across the board, these products are intended to improve both engine performance and exhaust sound compared to stock.

OE Compromises

On most original equipment, cost-effectiveness usually takes priority over performance. In exhaust systems, this translates to tubing that has "muffler bends"—kinks on the inner radiuses of each contour—and mufflers that normally trap sound using inexpensive fiberglass packing. Furthermore, OE muffler bodies are typically made of thin-gauge steel that's seldom fully welded at the seams. This is why factory mufflers rot both internally, as the packing degrades, and externally, as the body and seams corrode.

Aftermarket Advantages

By using better materials and more-expensive manufacturing processes, the aftermarket is able to increase cat-back performance, longevity and sound quality.

Backpressure is the Achilles' heel of exhaust systems. Anything that slows down exhaust flow from the combustion chambers compromises engine performance (residual gasses can remain in the cylinders) and generates heat. In turn, heat fatigues metal and weakens the system's structural integrity.

One of the most obvious ways to improve exhaust flow is to remove any kinks from the tubing, just as unkinking the garden hose allows water to flow freely. This is done with a mandrel bender, a machine that drags a metal ball through the tubing to ensure that the inside diameter remains consistent through the bends.

Most OE mufflers also use restrictive mufflers to trap sound. Exhaust passes through the muffler in a lazy-S pattern and goes through baffles into fiberglass packing. Each bend and baffle louver causes friction, which generates heat and causes backpressure.

In contrast, many performance mufflers are straight-through designs—exhaust doesn't have to snake through a chamber, and sound is absorbed through perforations into the acoustical material. These systems run cooler and last longer, and can be "tuned" by their manufacturers to sound more aggressive.

MagnaFlow Demo

The advantages of an aftermarket muffler-tailpipe combo are illustrated here by a MagnaFlow cat-back system on a '99 Mustang Cobra. The MagnaFlow kit includes the features described above. In addition, the Cobra system includes 2 1/2-inch-aluminized tubing with mandrel bends for optimal flow and long life. The tailpipes are capped with macho 3 1/2-inch, angle-cut stainless-steel tips.

However, most of the cat-back's performance gains—a manufacturer-estimated 10 horsepower in this application—are from the MagnaFlow Street Series mufflers. Featuring a straight-through design with internal acoustical-absorptive material and stainless-steel mesh, these mufflers also feature fully TIG-welded seams and mirror-finish T-304 stainless-steel bodies for longevity (they're warranted for life) and show-worthy aesthetics.

The actual installation of this MagnaFlow system and many other cat-backs can be an at-home undertaking. We used a lift to accommodate photography, but the job could be done in the driveway by jacking up the car and securing it on jackstands. The throaty rumble, extra push back in the seat and peace of mind knowing that the mufflers won't rot are worth the little bit of effort.

Resource

MagnaFlow Performance Exhaust Systems, (800) 959-9226, www.magnaflow.com