I used a drill with a bit that is a little larger than the diameter of the rivet holes. In order to determine the rivet hole size, you need to measure the replacement rivets in the new gasket kit. Anyway, by using an oversize bit, you cut out the ring-side of the rivet and stop drilling. Then you just punch out the rivet using the appropriate sized flat pin-punch. It's pretty easy if you got good eyesight and are careful to stop drilling as soon as the ring part of the rivet is cut off.