I wired a risistor accross the pressure sensor to fool the APC that it was operating in a normal range. I don't remember the exact value but 50 ohms sounds about right. The APC is set to like 5-7 PSI for normal operation. The resistor will fool it into thinking this.
I also had problems with the 3 way selonoid not being able to hold at higher boost levels. It would just let the boost keep rising. ANd I did try different Saab selonoids. I ended up using the old 240 selonoid and drilling out the oriface. Now if the engine pings the boost goes all the way back to the base setting. The 240 selonoid is not capable of "vibating" like the saab one. Let us know if you have the same problem with the saab selonoid.