Overboost system checks out.
Overboost valve closes when gound is applied.
The other wire is hot with engine running.
Overboost sensor was not plugged and shorts to ground at 16psi.

I think the overboost is working. 4th gear is the only one where 20psi was seen. After the 4th gear shift the car seemed to have hit a limiter.

__________________
I suggest we solve high gas prices with environmentalists... unfortunately they don't burn well.
1982 300CD, 220K miles: This vacuum system will be the death of me yet! (OBK #26)
1977 F150 400 C6 2wd, 10.2 sec 1/8 mile with 2.75 gears.
1965 Mustang. Mostly stock... LOL!
2001 Ram 2500, cummins, 5spd, 202k miles.(girlfriends)