CT I need your help! I've got one of these gfb boost controllers installed in my car. everything on the controller works fine, but I'm having trouble with inconsistent boost. Details in comments, any help is appreciated!

I’ve got the duty cycle, gain, and sensitivity dialed in fairly well, so my turbo will spool up to around 10.8-11.2 psi. the issue I’m having is that it only spools up this high around 50% of the time. other times it will only spool up to around 7.5-8 psi (stock boost levels). I have the N75 valve (the stock vw boost control solenoid) connected electronically, but plumbed out with a piece of vacuum hose. I tried disconnecting it, but i still have the same problem, only now on the “low boost” pulls, it only spools to like 4psi, but will occasionally still spool to 11. I also have a gfb dv+ T9301 diverter valve installed to help cope with the added boost. Any ideas what the problem is? I’ve checked my plumbing over 3 or 4 times, and i’m fairly sure it’s not a vacuum leak. I’m at a loss :(