Were your stock o-rings smaller than the BP o-rings? I just tried it with BP fatboy fittings and the Ghost Compressions o-rings and it was leaking without even turning on a pump

It was a fairly slow drip compared to the stock BP o-ring, maybe a drop every 10-15 sec, but still a drip

I know with the #9 o-rings, I can just hand tighten and have no leaks even at really insane pressures (on my 8-port Typhoon). When I tore down a couple days ago, I converted all my fittings to #9s, they're really awesome