How hard are these units to install?

Very simple. All of the installation is done from inside the car, without having to jack it up and crawl around underneath. Only a few basic hand tools are required, and the necessary hex keys are supplied.

How much is the throw reduced?

The maximum throw reduction varies for different models. Early WRXs had a particularly long throw, so the maximum reduction with the GFB kit is around 50%, whilst on later models it is closer to 40%. In either case, it is possible to reduce the distance per gate to about 30mm. Whilst it can go shorter, the shifting force becomes too great for comfort, and some of the shift feel is lost.

What does the ‘Whistling Trumpet’ sound like?

In normal driving conditions it gives a typical “whoosh” sound, but once the revs and boost level rise, a high pitch whistle noise takes over. Visit our sounds page to hear it in action.

Which blow-off valves will the ‘Whistling Trumpet’ work on?

The optional whistling trumpet works on the Stealth FX, Deceptor Pro and the updated model WRX Hybrid (not the old model WRX Hybrid or the 1003 Hybrid 'universal'). For the whistling trumpet to be effective, the BOV must be set to full vent-to-atmosphere, and boost must be at least 12 psi (0.81 bar).

The whistling trumpet does not work on any other blow-off valves due to their different airflow characteristics.