Your car sounds like one of those Warthog bombers from the Gulf War. So you know it's muffler time. Yet it's rare that a car needs only a muffler. Usually other parts are going, too: exhaust pipes, tail pipes, clamps and hangers.

The longevity of muffler and pipes depends on what kind of steel the components are made of, how pipes are routed under the car, where the muffler is located, and whether or not the vehicle has a catalytic converter.

Original equipment pipes made of aluminumized steel generally last five to seven years, except in areas with a lot of road salt and moisture. In these areas, pipes may need replacing after three to five years.

Original equipment pipes made of stainless steel (which are used from the converter forward on most cars and for the entire exhaust system on some) can last up to ten years or more.

Most aftermarket pipes, by comparison, are made of ordinary steel which is good for about three to five years of service. Aluminumized and stainless pipes are better, but cost more.

With mufflers, stainless holds up the best, followed by double-sided galvanized steel. Single-sided galvanized and aluminumized hold up fairly well, while plain steel offers little or no corrosion resistance.

As a rule, the hotter a muffler runs the longer it lasts. Mufflers on vehicles with catylitic converters run hotter and last longer than those on older vehicles without converters. Mufflers located ahead of the rear axle last longer than those located aft of the rear axle.

Under federal law, every catalytic converter in pre-1995 models carries a mandatory warranty of at least five years or 50,000 miles, and those on later models run to eight years or 80,000 miles.

Mufflers rust from the inside out. Rust is caused by moisture in the exhaust. Moisture condenses in the muffler when the engine is shut off and the muffler starts to cool. Some mufflers have a small pin hole that allows condensation to seep out.

One aftermarket manufacturer puts a small packet of a special moisture absorbing chemical inside some of their mufflers to fight internal corrosion.