Hissing Sound, T44TQ

[Larry C. Leung]

Okay,

Looks like I have a leak somewhere on my 200Q. Searching for
possible ideas. Symptoms:

1) Get nearly full boost from dash gage, car is chipped, usually sees 1.8
bar, now sees 1.7, car is still
        relatively responsive.
2) Hissing sounds when boost gets to about 0.9 to 1.0 bar. It's not too
quiet, sounds a little exhaust like.
3) Water and Oil Temps seem okay, so I'm not sure if it's right by the
head.

Any suggestions on where to begin to look, or how do I go about checking
for the leak?

TIA,

LL - NY        '89 200Q, chipped to 1.8 bar, new nickname, (not) Cobra