2011 WRX 100% stock here and I also recently installed the SPT gauge... my vac at ilde is 19.5. I've actually never seen my vac go past 20.
Boost hits right about 14.5-14.7
When you turn the car off does the needle sit EXACTLY at 0?
Also, I noticed you didn't install the final ruber piece that goes around the guage housing? I thought it added a nice final touch.