To help decrease turbo lag between shifts, I installed a CBV from a 700 series turbo.  A CBV is a valve that recirculates air from the turbo outlet back into the inlet when the manifold is under vacuum (like during a shift).  This allows the turbo to pump air back to itself and stay spooled up.  Without a CBV, when the throttle is snapped shut during a shift, the pressure from the turbo smacks against the butterfly, bounces back, and hits the compressor wheel.  This causes the turbo to slow down, thus requiring the turbo to re-spool when you get back on the throttle.  This buffeting of the compressor wheel also causes axial movement and wear on the turbo bearings.  In severe cases (20+ psi) it can actually destroy the compressor wheel.

Aftermarket CBVs can be purchased and installed but I chose to install a 'stock' CBV because I got it cheap at my local U-pull.  I also got the 700 series IC tubing cheap.  If I wouldn't have got a good price on the CBV, bracket, delay valve, and tubing, I probably would have opted for an aftermarket Bosch (0 280 142 103), Spearco, or similar unit.  I have been told that the stock CBV is really only good to about 15 psi.

The CBV basically mounts and connects the same as in the 700 series car.  I first mounted the CBV in the same place on the head as the 700 series motor.  I installed a couple of washers to space the bracket so it would mount nicely on top of the existing bracket that holds the fuel lines.  I cut into and removed the 'J' shaped hose from the 700 series rubber turbo intake elbow and attached it to the bottom of the CBV.  To get the maximum hose length I actually cut into the elbow to remove as much of the 'J' as possible.  You could probably use the whole 700 series rubber intake elbow in place of the stock metal elbow if it is in good shape (the one I got was rotten right at the turbo).  To connect to the metal 240 elbow, I added a 1" aluminum nipple and bonded it in place with aluminum reinforced epoxy.

I then used the metal 700 series turbo outlet elbow in place of the stock rubber one.  The metal elbow has a nipple to connect to the inlet (side) of the CBV.  Because the 700s don't have the fuel lines in the way the elbow is mounted lower.  To clear the CIS lines, I extended the turbo outlet hose with a piece of heavy duty blue silicone (1/4" wall, 2" ID, 5" long) tubing form Turbonetics.  Now because I moved the whole elbow up about 2 inches, the tube between the outlet elbow and the CBV didn't match up.  I needed an 'S' shape to do it right.  To connect these two points I went to my local parts store and looked through their preformed hoses.  I found that a Goodyear #61284 hose fit quite well.

To finish the installation, I connected the vacuum/pressure line to a spare nipple on the manifold.  The connection must be on the engine side of the throttle body and the arrow of the 'delay valve' must point toward the manifold to function properly.