Personally I would look at B1 stuff as a START. You will already need new pistonsif oyu go away from the -1 stuff. GUess you really need to ask what the goal is. If you were happy at the power level you had then go back to a -1 head. Port technology is always evolving and the latest and great port design by one of the big name porters out there may show a good gain over what you had. IMO what you had power wise is close to maxing out a -1head IMO, intake valve size, port CC just limit the power potential without going WAY up in RPM. I would look at the B1 original as a STARTING point if you want more power. Just my