• The right pipes will add to the performance of a Harley.motorcycle lines image by BorisNoWorries from Fotolia.com
  
  Most people are well-acquainted with the unique sound of a Harley-Davidson exhaust system, but sound levels do not mean power. The design and size of exhaust pipes affect overall performance by helping control airflow and gas emissions throughout the engine. Whether using stock or specialty exhaust pipes on your Harley, always choose systems made for performance before flash and noise. The right choice will improve the operation and value of the motorcycle.
  
  

Slip-Fit Mufflers

• Slip-fit mufflers are installed over the original exhaust pipes.pot d'??chappement d'une moto de l??gende image by ParisPhoto from Fotolia.com
  
  Slip-fit mufflers are a good idea from both an economic and installation standpoint, according to Harley-Performance.com. In addition to being able to keep the original stock exhaust pipes, the cost of a set of slip-fit mufflers is much less than a new set of Harley pipes. This type of pipe extension will improve a motorcycle's sound and performance through better air flow.
  
  

Two-into-One Exhaust System

• Two separate pipes join to form one exhaust pipe in this 2-into-1 system.Motorcycle Exhaust image by Billy Tait from Fotolia.com
  
  A two-into-one exhaust system is just what it sounds like: two exhaust pipes that blend into one larger pipe. This system does best on a stock Harley-Davidson engine. Although earlier models tended to sacrifice sound for performance, newer designs incorporate an updated removable disc technology. These discs can be easily added or removed to control both the sound and exhaust flow of the system.
  
  

Long Straight Pipes

• The right exhaust pipes can enhance a motorcycle's performance.bike exhaust image by Dumitrescu Ciprian from Fotolia.com
  
  Aesthetics aside, running longer-than-stock Harley exhaust pipes can add to both performance and sound, as long as the diameter of the head pipes don't exceed 1 3/4 inches. Anything larger will begin to drastically reduce performance. Nightrider.com recommends considering average engine RPMs, gas speed and exhaust temperature before choosing longer pipes. Most riders have no need for complicated drag pipe designs on an average street bike, and there are several straight pipe designs pre-tuned for a standard exhaust Harley-Davidson.