this discussion is about changing the exhaust on the City X. some people like to make the bike louder and get more performance (ie horsepower and torque) out of his or her bike. the cheapest way to do this is to change the exhaust. coming from the factory, most motorcycles are "leaned out" in order to meet the state´s emissions test. by leaning out the motor, some of the bike´s power is lost. after the bike is purchased you can modify the bike to regain this power. the easiest way to do this is to put on a high flow air cleaner, install a race ecm, and put on a performance (free-er flowing) exhaust. buell makes this kit. i cant remember the pricing off the top of my head but any harley dealership should have the p&a catalog for buell. by installing these parts you can gain about 5-7 horsepower and footpounds of torque. it also smooths out the powerband which eliminates the dead spots (lack of power when accelerating). if you have any questions feel free to email me. i work at the parts counter at a harley dealership and would be more than happy to answer questions.