Tuning FX Maverick VP w/ Slug Power Kit shooting 38.5gr NSA slug tune?

I just installed the thing, quite easily actually aside from losing the ball bearing and more, now my biggest question to those guys who have experience is what regulator pressures should I be setting this to? My goal is around 75-79 FPE of energy and when I dry fired it god damn did it sound different, it even did the swoooosh sound from front to back reg and I believe I'm @ 125 PSI on my front reg? Does anyone have any suggestions? I don't have my much room to work with, my rubber mulch is running out and 60 FPE went through it once actually so this REALLY scares me lol. I'd like to pretty much get it anywhere in the 75-79 in the first try. I'm thinking 150/125? Forgot to mention, I've never regulated it, had a company tune it, it's shooting 58 FPE I believe with 29 grain NSA slugs. and 60 FPE with FX Hybrids. The back pressure monitor says 125-130, maybe I'll leave it alone and take a test shot to see what it does even now? 
 
Your front regulator should probably be around 175-180BAR and your rear at somewhere around 130-140BAR. It totally depends on what you’re shooting and that’s a guess but the 38.5gr are heavy and have more drag than Diabolo pellets. My son has his set up at 175 and 135 and it shoots the 33.95gr JSB’s at about 915fps. There are other variables though. The front regulator should be quite a bit higher than the rear regulator. It drops the pressure from 250BAR to whatever you have it set and so the second regulator doesn’t have to work as hard and so it will be a lot more consistent. I can’t give you the exact numbers because we don’t use the 38.5gr NSA slugs. You should watch a tuning video on You tube so you can see how to adjust the first and second regulator. It’s not hard but it’s certainly different from setting up an FX with one regulator. It’s a process that you have to do in the correct order. Good luck.

Stoti