Boost Leak Help

[Elminsster]

Hey guys, any input or advice would be much appreciated. I have a 90 300zx TT. My car is on 15psi right now but wont hold it. In second gear it will hit 15 and then drop to 13-14psi and stay there. 3rd-5th gear it holds 15psi till about 4-5k then drops down to 13-14psi again. So I though I may have a boost leak. I tested it and found one at one of the charge pipes which was no big deal and I took care of it with ease. My problem is I think I found another one but it sounds like it is coming from underneath the intake plenum. It doesnt come from one specific spot it sounds like it leaking from all end of underneath the plenum. Any ideas?

[ThisIsSparTTa]

Obviously plenum gasket could be bad. Check the sides of your throttlle bodies though. The seals on the side for the linkage aren't serviceable and known to leak. Mine makes this terrible whistling noise when doing a boost leak test.

[Elminsster]

Thanks for the reply. Yeah my guess is the plenum gasket. I want to do a plenum pull anyway so I can do the deletes/bypasses. During the boost look test it almost sounds kind of like a sizzling coming from underneath the plenum.