Many Harley-Davidson riders swear by the aphorism "loud pipes save lives." And, after all, a confident rider is a safer rider. Making stock pipes louder is a less expensive alternative to purchasing an entire aftermarket exhaust kit. However, the only effective way to make that stock muffler louder is to remove the baffles, this can be done in four easy steps.
Coat the rear of the muffler interior with cutting oil. The cutting oil will help prevent smoke and sparks as you remove the muffler's baffle as well as keep debris from flying around and getting into the headers.
Use a power drill to cut out the baffle, the long cylinder in the middle of the muffler. Attach a drill extension and hole saw to an electric drill. Cut through the end plate surrounding the baffle opening. The baffle is welded onto the end plate at the back of the Harley. On some exhaust pipes, there may be a set screw holding the front of the baffle in place. This can be removed with an Allen wrench or screwdriver.
Grasp the baffle with a pair of needle-nose pliers. Twist and pull the baffle until it slides out. This may take some effort. Once the baffle is out, inspect the pipe for metal shavings. You may want to remove the muffler to blow air through it to ensure no shavings are left. Or you can simply remove the muffler, hold it upright and slap it with your hand to ensure the path through the muffler has no debris in it.
Repeat Steps 1 through 3 for the other muffler. Replace the mufflers on the motorcycle and take it for a test-ride.
Be aware that removing the baffles can change the compression ratios for the motorcycle that can affect the power levels delivered by the bike.