Hints for finding a boost leak
(taken from this thread http://forum.lotuselancentral.com/viewtopic.php?f=31&t=18941) A very cheap test rig can be put together using a bike inner tube. A mountain bike tyre is more suitable than road bike - I used one for tyres up to 2.125" diameter which is a tight fit over the turbo intake.
Cut the tube in half a short distance from the valve. Tie a knot in the short end. Remove the ribbed hose from the turbo intake, and fit the other end of the inner tube over it (I found rolling it back on itself slightly allowed it to be pulled/stretched over the intake). Use the a jubilee clip to secure it:
A footpump can then be used to pressurize the intake system:
After a few pumps, listen for any hissing around the turbo hoses, down to the intercooler, and back up and around the intake plenum. If it's hissing, you've got a leak.
The bike tyre will inflate fairly quickly even though the overall pressure in the system is low. Keep an eye out for it coming off the intake though - if it does it will be with a very loud bang!