Well after a back breaking examination of the drivers side dash I finally located the problem. As the picture demonstrates there is black electrical tape wrapped around the line that leads to the boost gauge. The tape is wrapped around the line just before it goes through the firewall. I mashed the tape around the line with my fingers and the hissing stopped. Obviously somebody did a hack job and thought tape would solve the problem. Does anyone know where I can find a suitable replacement line? Also, would this leak have any other effects besides a sluggish boost gauge? The odd thing is I have not noticed any irregular boost readings when I am at WOT.

 

Its prob. something to do with the intake!

 

See if your boost guage is working -

Follow the vacuum line from the intake through the firewall into the back of the dash ...
Good Luck - if its in thecab its gotta be the Vacuum for the Heat and AC or the boost guage
Doug

 

That's my guess. I had my bosst gauge T pop off while I was going past the 1/8 mile marker a few weeks ago.

 

Bump, see the original post I updated it with a picture of the problem.
(I did not realize editing a post would not bump it too the top again)