GFB's whistling trumpet, as the name suggests, gives off a unique high-pitch whistle sound on gearshift.

It is a direct screw-on replacement for the standard trumpet found on most GFB valves, and is recommended for use where peak boost pressure is above 13psi.

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The ability to change the sound of a blow-off valve is increasingly becoming an important issue with buyers, who want to sound different from everyone else.

In 2004, GFB released the Whistling Trumpet (part # 5701), which emitted a piercing screech when driving aggressively. Unfortunately for a number of GFB owners, the 5701 trumpet only worked with Stealth FX, Deceptor Pro and WRX Hybrid valves.

For the owners of all other types of GFB valves, we have now released the 5702 – a modified version of the Whistling Trumpet that is designed to work on Mach 1 and all Hybrid variants, and importantly, on low boost applications where the 5701 doesn’t cut it.

The 5702 can be used in place of the standard trumpet on all GFB valves, and will make the whistling sound more readily than the 5701 (high boost and RPM is required to get the whistle from a 5701), and at a slightly higher pitch. Like the 5701 however, it is necessary to run the valve so that all (or most) of the air vents through the trumpet – Hybrid valves will typically not generate the velocity required to whistle when set to 50/50 venting.