4 speed ka-booom !

Noted in pic is where I taper them back so there not a flat, straight edge, which help's tremendously, while shifting!
View attachment 1714847715

How far do you taper them back? Do you have a picture of a modified hub?
Just to be sure are you talking about the sides of the "teeth" or the front and rear flat area or the top (the arrows point at the corner so I'm not 100% sure)?

what do you use for tapering and how do you get them hardened (nitrating, cryo-treatment, heating/cooling)?