Well, that's pretty funny.... The original system used vacuum to keep the wastegate shut, and when boost increased, it modulated the vacuum to allow the exhaust pressure to push the wastegate open. By applying manifold pressure to the actuator all you do is force it to stay open all the time. You'll be lucky to get 3 psi of boost that way. I suppose if you put a big spring on there to pull it shut and then used manifold pressure to override the spring, you might be able to get something to work, but a lot simpler is just use a spring to pull it shut and allow exhaust pressure to push it open. I did just that one day when my vacuum pump failed, so I could get home pulling my horse trailer.
The Constitution needs to be re-read, not re-written!
If you can't handle Dr. Seuss, how will you handle real life?
Current oil burners: MB GLK250 BlueTEC, John Deere X758
New ride: MB GLS450 - most stately
Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510