Just measured the official RE sprocket removal box spanner for you. As I thought, it's 46mm, the same as the wheel nut on a Triumph Sprint ST FWIW. As for the gearing that depends on how heavy you are, whether you ride solo or two-up, where you usually ride, whether you are a top gear cruiser type etc. Me, I find it much better with the 19 t sprocket. Don't confuse opinion with fact.