For speaker holes the harbor freight hole saw cuts like butter. The 5" is perfect for most 6.5 speakers. For bigger holes, i start with the hole saw and then open them up with a dremel or roto zip. For even bigger holes the size for 10" subs, i use the hole saw to get started then use a jig saw to make em bigger. With the hole saw, make sure to use a regular corded drill. Cordless doesnt cut it.