I am having an issue with low vacuum at idle(-10 to -12), which after a few seconds creeps back up to the correct -15to -17, and my boost is 2 psi low at full.

Things that i thought could affect it:
I have recently replaced the hotside of my turbo since my divider wall was folding, and when I reattached the wastegate actuator i made sure it was taut and had to pull it up about 1/8th in out to get it onto to arm... that is enough, correct? only other thing i could think of was exhaust leak but there is none, and i especially took extra care to make sure the halves of turbo were put together flush with dowel pin in place and clamped firmly.

what i think it is:
After i started the car, let it idle, drove a bit, washed it....lol.....ayways after a while of driving i opened it up and was still a couple psi under boost (21-23 max when tuned for 25ish) and tapering and barely holding to 17 by 6500 rpm... also having a bit of a low idle/vacuum at idle as well.... i ran a boost leak test and could hear air coming ONLY from my aeromotive fpr. this isn't this normal is it? i ask bc i know aeromotive fprs have a history of being faulty, a light high whistle of air was coming from the housing of the unit... or do they always do that?

Please chime in if you have any useful thoughts or advice on what to check next or if whats going on with my FPR is probably causing the issue.

in case you're wondering, the car has exhaust, intake, intercooler, double pumper w an lines, aeromotive fpr, 1200s, gsc 280 cams springs& retainers, and buchur racing stg3 short block. the car is tracked and the problem was noticed 2 or 3 weeks ago after a day at msr, and more pronounced after this last friday i had it out. problem still there after hotside replacement.