FX Widcat .22 regulator pressure

Guys:

Based upon the excellent review made by Chuck (http://www.airgunnation.com/topic/setting-the-regulator-hammer-spring-tension-correctly/#post-222976), I decided to order a Huma regulator for my Wildcat .22. 

I can ask them to preset the regulator pressure which I will. FX site non updated specs says 140BAR for the original regulator. However I think it is 120BAR. I shoot JSB 18.13 grains and I have an average of 886FPS. My current spread is 15 FPS which is unacceptable. I cautiously have changed the orings and nothing. Same spread. 

Anyway, what my fellows airgunners recommend as the optimal regulator pressure having in mind my current pellet weight and caliber?