WHAT IS THIS... HELP

[SAD VR6]

Can some tell me what this is il try to describe the best i can
1992 mk3 Vr6
OK  The pipe from air box to throttle body has a pipe coming from the back that looks like it goes into the head, off this pipe is a small connecting pipe which goes to a blak box with 2 other pipes going into the head.... The box is about 4x3 inches has rounded top corners.. the two pipes that come from it hold the two water pipes that go from throttle body to water header
This sounds like its leaking air but what the hell is it??

Thanks in advance
Mark

[SLIM-DUB]

dunno but mine does exactly the same thing! a kind of hissing sound  will try and find out now,as im curious too! 

[AudiA8Quattro]

Post a pic, and i'll tell ya what it is.