This is a terrific, cheap and easy swap out (under the seat 2 screws on Softails).
Pick up about 3-4 HP trading out the factory EPA rated part.... lil carb mods, Stage 1 air filter and pipes... your bike will gain a bunch of PEP!
After just add the cam of your choice (Andrews EV 27) if you like... 6-8 more HP!!!
Don't forget the Iridium plugs!!!!