GFB T9503 User Manual

Deceptor Pro II Blow-off Valve

Installation Instructions

P.O. Box 1017 Riverwood NSW 2210

Ph: [phone] Fax: [phone]

Website: www.gfb.com.au Email: [e-mail]

Fitting Instructions for GFB Deceptor Pro II (part # T9503)

(fits MY01–07 WRX, MY01-on STi, and MY05-08 Forester XT)

Included in the T9503 kit:

 Deceptor Pro II blow-off valve
 Electronic in-car volume controller

 Double sided mounting tape
 2 x stainless steel mounting bolts

Thank you for purchasing the GFB Deceptor Pro II blow off valve. We highly recommend that you familiarize
yourself with the operation and adjustments of the Deceptor Pro II before installing it.

Installing and wiring the in-car volume controller

1) Test the unit before installation by connecting the Deceptor Pro II’s plug to the in-car controller. Connect the

red wire to the positive terminal of your car’s battery or a 12V source. Connect the black wire to the negative

terminal. Upon initial power-up, the unit will perform an open/close cycle before reverting to the position
indicated on the controller dial. By turning the dial and watching through one of the valve’s venting outlets,
you will see the inner sleeve move to open or close each of the venting ports alternately, which is how the
venting volume is adjusted.

WARNING: Do not manually rotate the noise adjustment, always apply power and use the controller
to change the venting bias. When testing your Deceptor Pro II, DO NOT put fingers or foreign
objects through the trumpet or plumb back ports. Doing so may result in personal injury or damage
to the blow-off valve.

2) Find a suitable location on or around the dashboard, steering column or instrument binnacle for your in-car

volume controller. Clean both mating surfaces with Methylated Spirits or similar cleaner and secure the
controller using the supplied double-sided tape. Press hard and hold the unit for about 30 seconds, and note
that it takes up to 24 hours for the tape to develop a strong bond.

3) Using a multi-meter or voltmeter, find a suitable power wire that reads 12V only when the ignition is turned

on. Solder the end of the volume controller positive (red) wire to the 12V source. It is possible to use a wire
tap or crimp instead, but soldering is the most reliable joint. Make sure to insulate the joint properly.

4) Find a suitable bolt on the body/chassis and connect the unit’s ground (black) wire to it.

5) At this point you should plug the Deceptor Pro II back into the in-car volume controller, and test its operation

again to ensure the electrical connections are good. Make sure the unit powers on and off with the ignition.

6) Unplug the Deceptor Pro II and pass the controller’s extension lead through the firewall into the engine bay.

Often there is an existing grommet that can be used for this purpose. In any case, it is important to ensure that
the lead is protected where it passes through the firewall to prevent wear or damage.

Installing the Deceptor Pro II blow-off valve

On Impreza models without an electronic throttle, it is necessary to move the intercooler to gain access to the hose
clamp under the factory valve. It does not need to be removed completely; it just needs to slide back far enough to
reach under. These instructions take you through it step-by-step.

For Impreza models with an electronic throttle and also Forester XT models, it is usually possible to access the clamp
without shifting the intercooler. In this case, simply ignore the steps 1, 3, 4 & 5.

1) Pull the hoses from aluminium tubes that run

across the front of the intercooler (there are
two on the left and 1 on the right. See figure
1, step 1).

2) Using a 12mm spanner (wrench), undo the

bolts that hold the factory bypass valve and
remove, leaving it supported by the hose.
Take care not to drop the bolts or gasket
from behind the valve (figure 1, step 2).

3) On the short hose section between the

intercooler and throttle body, loosen the
hose clamp closest to the intercooler.
Loosen the clamp holding the hose onto the
outlet of the turbo (figure 1, step 3)

Figure 1

4) Undo and remove the two mounting bolts (again

using the 12mm spanner) that hold the intercooler
in place (figure 1, step 4).

5) Carefully slide the intercooler back just enough to

access the hose clamp under the valve (figure 2).
Take care when handling the intercooler since the
cooling fins are very fragile, and also take care not
to bend the plastic hose from the turbo too much.

6) Take note of the position of factory valve and then

use pliers to open the recirculation hose clamp
(figure 2). Remove the valve from the recirculation
hose and vacuum hose.
Figure 2

7) The Deceptor Pro II comes supplied with a new gasket that must

be used in place of the existing factory gasket. If the factory
gasket is stuck to the intercooler, use a knife blade or similar to
free one end, then carefully peel it off. Make sure there is a clean,
flat surface left for the o-ring to seal on, remove any remnants of
the gasket before proceeding.

8) Now unscrew and remove the return nozzle from the factory

valve. Fit the return nozzle to the outlet of the Deceptor Pro II as
shown in figure 3, using the screws and the o-ring from the
factory valve.
Figure 3