SINGLE STACK This exhaust pipe comes from behind the fuel tank, behind a protective cover, and up past the passenger compartment. In this case the stack is on the passengers side. This is normal if there is only one stack. On the theory that the driver usually sleeps with his head on the driver's side of the truck. (Photo `04 Manzanillo, Mexico)	TWIN STACKS. This is also a good picture of a bullboard (headache rack). Note the hanging chains and boomers.

The law requires that exhaust fumes be carried beyond the driver/passenger compartment of any vehicle.

The protective shield on the exhaust pipe is to prevent a person, while getting in or out of the truck, from being burned on the hot exhaust pipe.

There should be a muffler behind the protective cover, often there isn't. This is referred to as a straight pipe.

Straight pipes, or a hole in the exhaust pipe, before the muffler, is what cause Jake brakes to be so loud. Jake brakes are almost unnoticeable if a truck is equipped with proper mufflers. (Most large busses, (i.e.: Greyhounds) run Jake brakes but no one complains about the noise because no one can hear them, because busses use proper mufflers.)