The internal combustion engine is a wonder of ingenuity and engineering. Over the last century the design has been tweaked and tuned for more power, efficiency and lower emissions. Complex gadgetry?electronic, mechanical or otherwise'is par for the course and the modern engine seems a far cry from those humble old mills that Henry Ford was tinkering with.

The one thing that remains constant through the years is that the internal combustion engine is simply a large air pump. Make no mistake, whether it's the 5hp Briggs & Stratton on your lawnmower or the 400hp supercharged powerhouse on your Mustang Cobra, it's still just a pump. Air from the atmosphere sucks in, does its thing, then pumps out as exhaust gas?simple.

If you think that pumping more air equals more power, you are absolutely correct. The most popular products in the automotive aftermarket are air intakes and exhaust?products that get the air pumping. Let's take a closer look at the latter: performance exhaust and headers.

Performance exhaust works by simply getting more air out, as we covered earlier. Aftermarket exhaust usually means larger diameter tubing and higher-flowing mufflers. The bends are done with a mandrel, which means the diameter stays true through the length of the pipe. Normal bending squeezes the tubes at the bends which causes restrictions in flow.

Higher-end kits are actually tuned to create some backpressure which results in a phenomenon known as exhaust scavenging. As the exhaust flows through the tube a vacuum effect begins that essentially sucks the gasses out of the chamber, rather than them being pushed by combustion. Scavenging is the magic behind performance exhaust.

Another benefit of performance exhaust is the sound. When you hear that throaty roar, it can only mean one thing?power. Whether it's the low, deep rumble heard while idling at the light or the screaming wail let off while the needle tickles the redline, there is no mistaking the classic sound of a quality exhaust system.

The front end of any true performance system is a set of headers. Most engines come from the factory equipped with a heavy, cast-iron exhaust manifold. Not only do these things weigh a ton, they are constrictive by nature. A nice set of headers is made of lightweight tubing, the best being T-304 stainless steel. They not only increase exhaust flow, they shave excess weight which can be the difference between the checkered flag and sucking dust.

Performance headers also offer a lot in terms of tunability. Depending on how they're shaped, a tuned header can increase low-end torque, top-end speed or mid-range drivability. The one drawback of headers is that installation can get pretty difficult. Engine bays are traditionally filled to the gills and trying to thread 3 feet of odd shaped tubing through this menagerie can get maddening.

There you have it, for any serious performance project, a set of headers and a nice exhaust system is a must. Street rods, cruisers, trucks, sport compacts?even family sedan come alive when allowed to breathe freely. Toss in a cold air intake and a performance chip and you'll be chewing up the competition all over town.