Blow off valve
The picture above shows a Bosch bov. It is commonly found on Saab 900 turbos, but works on many applications. I read on the net that it is good only to 10psi of boost before it starts to leak. With my own experience at 15psi, I have not had it leak yet.
It was a simple install on the CA18ET. Simply machine weld a outlet onto the main pipe to create a "boost loop" and it will work. You CANNOT vent the boost to the atmosphere. The AFM has metered a specific amount of air for the engine to work properly. By venting it out, the engine will have serious driveability problems! Vent it back to the intake and you will have a big grin on your face each time you boost!
Here is another picture of the whole engine bay.
Observations with the bov. Works great! Before the install, the turbo would make a whining sound each time I let off the gas to second gear. It sounded like something was about to break. It was also noticably hard to reach full boost after each gear change. It is a completely different car now. All the above mentioned syptoms disappeared with the bov. This is a mod I would highly recommend.