Adding a boost controller to your Audi will enable you to manually adjust the amount of pressure that the turbo in your Audi is outputting. If the turbo is producing more boost, then your engine will also see correlative power gains as the turbo spools up and becomes fully engaged. Not all Audi engines are equipped with turbochargers, so it is important to note that you cannot install a boost controller unless your engine is equipped with a turbocharger. The exact sizing and assembly of your engine will differ slightly from model to model.
Mount the boost controller in your interior. Depending on the model of boost controller you've bought, there may or may not be a standard dashboard mount included. A cheap mounting option is Velcro or double-sided tape, both easily obtained at most hardware stores.
Using the sockets and open wrenches, remove the plastic air box at the front, driver's side corner of the engine. Unclip the wide hosing that attaches it to the engine's intake manifold and set the air box and hosing aside. Disconnect any wiring harnesses that are attached to sensors in the intake tubing. Removing these components will give you easier access to the turbocharger assembly.
Remove the wastegate frequency valve, mounted at the top of the turbo. This valve is plastic, has a U-shape and has two small hoses attached to it that run from the turbo assembly. Pull the hoses out with the valve and set them aside.
Mount the boost controller's actuator to the wastegate frequency valve of your Audi. Depending on the model of boost controller that you're working with, the specific mounting process will vary. Fundamentally, you are connecting the actuating mechanism and hosing to the wastegate valve. The boost control device inside the car will electronically dictate the actuation of the wastegate valve and flow of air through the modified hosing.
Determine a location for the boost controller's input hose. You can route the input hose into existing hosing that is attached to the turbocharger's inlet.
Run the wiring from the actuator through your Audi's firewall, which is the barrier between the interior of the car and the engine. There are multiple small holes in the firewall through which you can snake the wire. Once it is has reached the interior of the car, strip off a bit of insulation from the end and wire it to the boost control device. Insulate this electrical connection with electrical tape.
Reinstall the wastegate actuator valve, the air box and intake manifold tubing. Remember to reconnect any sensors that you may have had to disconnect during the installation. Close your bonnet, then follow the calibration procedure that your boost controller requires before it can be put to use.
Each model of manual boost controllers is different, so be sure to reference specific wiring and installation instructions that may be included with the controller that you are installing.