If you have ever refitted your 4mm vacuum hoses for silicone hoses (a must do in my opinion), you will have noticed a little black box with three hoses connected to it. Have you ever wondered what that box does? I sure have.

The box works as a control for the turbo bypass valve, when the box is disconnected the turbo bypass valve is "hooting" a little under light throttle. This is kept under control by this valve, reducing the noise under the hood. When you bypass this valve you will get a more responsive throttle feel.

What you need to do is the following.

1. Disconnect the vacuum line from the throttle body and cap the throttle body vacuum exit.
   You can do this by cutting 35 mm of vacuum line, plug it with a screw and make it durable with a hose clamp (see image).
   
   
2. Disconnect the top one of the two hoses running to the manifold connection op top of the engine.
   
   
3. Connect the bypass valve (/ recirculating dump valve) directly to the top manifold connection on the engine you just disconnected. If your Saab has a T-splitter somewhere in the lines you are replacing you can add the T-splitter in the new line between the manifold and the bypass valve.
   
   
4. Remove all the excess vacuum lines connected to the valve on the firewall but leave it electrically plugged in.
   
   
5. All done, reset your ECU by unplugging the battery for 30 minutes to get a fresh start.

I have tried to clarify the connections by adding the pictures below.

This modification has been published by Nick Taliaferro, one of the Saab tuning guru's! i have felt the need to explain it in a bit more details.