The last generation MP distributor was a good design with the plastic keys for setting advance. That design had a lot of adjustability but you had to take it all apart to make changes. The MSD pro billet has some adjustability but not a ton. Out of the box it is limited to 16 degrees of advance so you can run 20 initial and 36 total. I eventually gave up on mechanical distributors and switched to digital just because of these issues.