Internal combustion engines produce exhaust gases as a byproduct of the combustion process.  In general, exhaust gases are expelled through an exhaust manifold which is designed to collect exhaust gases from one or more cylinders.  The exhaust manifold is connected to an exhaust pipe which communicates exhaust gases into the open air.  Internal combustion engines suffer from common drawbacks associated with the use of exhaust systems.  In particular, exhaust gases which move through bends and past obstructions within exhaust pipes, mufflers, and/or catalytic converters serve to reduce the performance (i.e., lower peak engine power, lower gas mileage) of the engine by creating back pressures.  Therefore, reducing back pressures within the exhaust system causes the engine to operate more efficiently, provides enhanced performance, and increases the gas mileage of an internal combustion engine. 
Previous attempts to reduce back pressure within exhaust systems include removing or modifying the exhaust muffler.  However, such attempts are replete with drawbacks.  For example, removing the exhaust muffler eliminates one source of the back pressure, but also results in non-desirous engine noise.  Other attempts to reduce back pressure within exhaust systems include positioning of a turbine within the exhaust pipe to draw the exhaust gases from the exhaust pipe.  The internal turbine may be powered by the motion of the exhaust gases or be powered by a power source, such as an electric motor within the exhaust system.  However, internal turbines powered by exhaust gases alone produce little effect.  The efficiency of an internal turbine may be increased if the internal turbine is powered by an electric motor; however, electric motors operating within an exhaust pipe are subjected to high temperatures and corrosive effects from exhaust gases passing through the exhaust pipe.  Electric motors operating in high temperature environments suffer from increased wear and tear and therefore require more frequent maintenance. 
In other attempts to reduce the back pressure of an exhaust system, an external turbine is positioned such that the blades of the external turbine are disposed about the exhaust pipe near the discharge end of the exhaust pipe.  While use of an external turbine has met with success, this design can limit the air flow that reaches the external turbine due to the obstruction of air flow by the exhaust pipe itself.  Further, the amount of surface area of the blades available for receiving air flow is reduced for a turbine having a selected diameter due to the space filled by the exhaust pipe, thereby lowering efficacy of the system. 
Therefore, a need exists for an exhaust evacuation apparatus that reduces the back pressure of an exhaust system, and improves the efficiency and performance of an associated internal combustion engine while avoiding the drawbacks of the previous systems.  It is to such an exhaust evacuation apparatus that the present invention is directed.