Adrian,
We are getting a little off topic with these 40 size clones. But while we are here: the parts do interchange with OS and they are true ABC but if you look at them closely they do not have the same type of chamfered ports and port design is one secret to power. The Performance Specialities sets make the most power because of thier port timing and port design.....scavaging is the secret my man.
PilotFrog