When a PCP is tuned for a "Korean Cliff", small changes in pressure cause large changes in velocity.... When you tune near the top of the curve (3 shots in 4-5% ES, or 2 equal shots).... then the velocity is much more constant over larger pressure changes.... That is because you are operating at the top of the velocity curve for that pressure range....Bob
Adding spacers is just like adding preload on a hammer spring adjuster or PW on a AF gun. Just not as adjustable but still do able.