Desperate for Help With My A4... Turbo/Hose Problem?

["Wehrer, Greg R." <GWehrer@ssd.com>]

I hope someone out there can help me with suggestions or ideas for  what
could be causing a problem I'm having with my A4 1.8T.  I think it may be
turbo/hose related, but judge for yourselves.
The deal is this:  I've got a chipped 1.8T-- the chip increases the boost to
14psi.  I've also got a pretty loud moan/groan/drone from the engine
compartment whenever the engine is under load (i.e. accelerating with the
pedal more than halfway down).  The noise is loud and constant as long as I
keep the pedal down.  It stops immediately on letting off the gas.  The
noise starts at the same time you would normally hear the turbo spool up--
you can still hear the turbo whine a little underneath the groan.  I can
also feel it vibrate slightly through the floorboard (probably because the
noise is deep).
Another interesting point is that, while the noise still occurs with the
stock chip in (the chip is socketed), it is MUCH less noticeable.  Not as
loud, and happens only in certain high-engine load situations.  Also, the
car doesn't feel as quick as it did with the chip in before this noise
started.
Other relevant information is that the version of the chip I had in when the
noise started apparently was putting out too much boost (17-18 psi, rather
than 14).  I've replaced the chip with a newer version, but the noise
remains.  I've already had the turbo replaced, and the noise hasn't stopped.

Does anyone have any thoughts about what this could be caused by?  The
dealer has been unable to identify the problem. 

Thanks for reading this treatise.