possible plenum/intake mani leak?

[SunshineAcid]

ive been hearing this noise for the past few days, and ive been trying to figure it out. it only happens under moderate to hard acceleration, and is very audible. its not grinding, just, it sounds like an open intake. tonight i popped the hood and tried to source the noise in the engine bay (which is hard, because it only really does it under load) and it seems to be coming from below the intake runners. the only other thing i can think of is when youre looking at the engine under the plenum, you are in the direct line of the lower side of the exhaust manifold, so maybe my gasket is gone?if anybody has had any experience with this, please let me know.other info:89 -> sohc to dohc swaptook apart both exhaust mani's and intakes to do the swap (both gaskets looked ok)noise seems to be coming from *under* the DE plenum

[eddiec]

you can do a vacuum leakdown test on the intake.