Power is the Holy Grail for most motorheads. We want a suspension that will flex like crazy, tires that will grip like a boa constrictor, and body armor that will scare rocks and trees out of the way. But when all else fails, power under the hood can make up for it. Why else is there the slogan, "When in doubt, power out"? No one says, "When in trouble, shift into double (double low, that is)" or, "When in a mess, let that suspension flex." In the dirt, hitting the throttle has saved the day more than once.
Getting power is a fine recipe of fuel, air, and spark. We're here to talk about airflow, specifically the flowing out of old air. A good exhaust allows said stinky air to escape, improving performance and usually fuel economy as well (a rare occasion of having your cake and eating it too). Plus, if you're lucky, that same exhaust will give your truck a throatier rumble that will add to the enjoyment of your new better-performing truck.