Hay Scott,
No cat on my car. I have to swap one in for emissions testing but I run the stock chip and drop the FP to like 35-38 when I do.
The car is an 89 TTA with right at 27,900 miles. I was thinking about a weak spring in the actuator as I know mine is not a moded stock one but I still do not know how old it is. I have a buddy with a 22K 87 GN running a thrasher for stock injectors, other free mods, as well as a good fuel pump. He put on an adjustable last year that he bought brand new from one of the vendors, Kirbins I think. Guess what, he gets a 2 to 3 psi spike as well. That's why I decided to look into a manual boost controller.
As for the 20 psi, oh it sucks!!! Gotta hat watchin needle on the boost gauge go from 10 hg of vac to 20 psi boost in no time. heheheh
Brent