GFB Deceptor Pro II Blow-off Valve (part T9503) - Manual (Page 4)

9)
Remove the trumpet by unscrewing it in an anti-
clockwise direction from the Deceptor Pro II to allow
the mounting bolt to be inserted into the hole (see
figure 3). Once the valve has been bolted to the
intercooler you can replace the trumpet.
10) Push the return nozzle into the recirc hose in the same
way as the factory valve, and replace the hose clamp
(figure 4).
Figure 4 (earlier version Deceptor Pro shown)
11) Slide the intercooler back into position, then bolt the
valve onto the intercooler using the supplied gasket
and stainless steel screws, and tighten them with a
5mm Allen/hex key. Push the vacuum hose onto the
brass nipple, and then replace the trumpet (figure 5).
Don’t forget to replace the intercooler mounting bolts
and tighten the intercooler hose clamps.
12) Connect the Deceptor Pro II’s lead to the plug from the
controller, ensuring that the whole cable is secured in
the engine bay away from direct heat sources or
moving parts.
13) Bundle any excess cable under the dash and cable tie it
securely. Figure 5 (earlier version Deceptor Pro shown)
Adjusting the spring pre-load
Contrary to popular belief, the spring pre-load DOES NOT need to be adjusted to suit different boost levels. Unlike
other valve types on the market, the Deceptor Pro II will stay shut under full throttle conditions regardless of
boost pressure or spring pre-load.
The spring pre-load affects how easily the valve opens when you
lift off the throttle, and how long it stays open when it vents.
Adjusting the spring is a simple matter of ensuring the valve
opens enough to release the air, but not long enough to cause
idling problems.
Note that there is no substitute for experimentation with the
spring setting, because different cars in different climates and
with different mods will unsurprisingly respond differently. Do
NOT be afraid to experiment to find the optimum setting, you
can’t hurt the engine or turbo by doing so. The guide below will
walk you through the steps involved.
The screw in the centre of the head is the spring pre-load adjuster
(figure 6), and the direction of adjustment is labelled (+ direction
increases spring pre-load). Use the supplied 5mm hex key for
this screw.