Had a Ken Graham high output concave in the previous combine here, wouldn't bother with another, had good output but v hard to get a nice clean sample, had to drive it on as
@laoisfarmer said but that didn't always suit as header, sieves, walkers or returns could be the limiting factor that determined forward speed in any crop. It also was slightly off true from new which didn't help and didn't get much hearing.
I'm changing the one in my current combine this year, waiting for one to come into Bernard Byrnes from Germany.