Quote Originally Posted by alan opel View Post
why before throttle body? the same vacum is feeding my boost guage and it seems fine? about 4 turns! 1/4 of an inch!
The pressure before the throttle body is higher than in the manifold, it's also more stable etc.
The manifold pressure is perfect for a boost gauge.

Keep shortening the threaded bar ,you mightn't have it short enough yet.
Needs a fair bit of pre-tension on it.