Our South African 101 owner should be up on AVA soon. Thanks!
He's looking to get max performance out of a pyra steel valve version 101.
I was never able to get max performance out of the old conical valves but that was before Byran and Assoc started remanufacturing parts.
One thing that I always found helpful was making sure that the air chamber is properly sealed with an O-ring. So, I would pop out the air chamber and, using a lath, cut a channel for an O-ring on the pump end and reinstall. Then, I would upgrade the gun to use the latest valve assembly with good results. Would be interesting to hear what folks have been doing with their 101's these days.