Yoshimura motorcycle exhausts are typically held together by rivets for a custom look. These rivets also hold the end plate onto the body of the muffler. Internally, the muffler has a series of baffles that the end plate holds together. If you want to remove the baffles for a louder sound or more performance, you have to remove the end plate and, therefore, remove the rivets. This requires drilling out the old rivets, so everything will come apart.
Park the bike on a smooth, level surface so there is no chance of the vehicle moving one way or another.
Insert a 1/8-inch drill bit into the drill. Place the tip of the bit in the centre of the rivet you want to remove and drill until it punches through the centre of the rivet.
Step up bit sizes progressively from 1/8 to 3/16, then to 1/4. Increase the bit size until the head of the rivet spins off of the exhaust, separating the two pieces. Repeat the process for any additional rivets you want to remove.