Cobrajr122, good to know that the whurring isn't just my imagination since I'm pretty sure I did hear whurring when decompressing my PSG-1 in the past in stock form. If your PSG-1 with some upgrades still has the whurring sound when decocking then I think my concern is legitimate i.e. that if I don't hear any whurring it's probably not decompressing. Someone on another forum thinks it might be the super strong neodymium magnets in the Systema magnum motor that isn't allowing the spring to relax.
From what I remember when my PSG-1 was still stock, after decompressing and hearing the whurring sound the decocking lever did not have any resistance any longer. So I'm deducing that no resistance on the lever = already decocked. Is my memory correct in that after you decock your PSG-1 the lever has no more resistance?