[BLKMGK]

I use the GM solenoid, the Apexdi is better since it's failure mode is minimum boost and not max I prefer having the AEM take care of the boost, one less blinky thing in my cockpit...

 

[BLKMGK]

I just looked at the log I've got for the spoolup thread I had started awhile back. 4th gear WOT it sticks to within 4KPA up to 5700 where I shut it off. Varied from 234KPA to 238KPA or so. Not sure what that is in PSI. That's with a 239KPA target so I tend to undershoot just a hair - that's a function of how I've got it setup is all. I could fine tune the duty table some more so that less adjustment was done by the error control which could smooth it a touch more but I've not bothered. I think within 5KPA is pretty good!