GFB Whistling Trumpet VTA Blow-Off Valve Twin Kit – Alfa Romeo Giulia / Stelvio Quadrifoglio | 2.9L Biturbo V6 | T9416-2

Quadrifoglio (2.9L Biturbo V6) only — does not fit the standard Giulia or Stelvio with the 2.0T 4-cylinder. Confirm your vehicle is the Quadrifoglio variant before ordering.

Twin kit — includes two BOVs, one for each turbocharger. VTA (Vent-to-Atmosphere) design — produces audible BOV sound on throttle lift. Not a recirculating / silent setup.

GFB T9416-2 Whistling Trumpet VTA blow-off valve twin kit for the Alfa Romeo Giulia Quadrifoglio and Stelvio Quadrifoglio with the 2.9L Ferrari-derived biturbo V6. Replaces both factory recirculation valves. Two BOVs included. 2.2 lbs. Ships fast across Canada and the US.

GFB Whistling Trumpet — VTA Sound Signature

The Whistling Trumpet is GFB’s signature audible BOV model, engineered to produce a distinctive high-pitched whistle and trumpet tone on boost release as the valve vents to atmosphere. The sound character is created by the valve piston geometry and vent port design — sharper and more defined than a generic aftermarket BOV ‘pssh’. This is not a subtle or recirculating upgrade — the Whistling Trumpet is specifically for builds where audible BOV presence is a desired outcome. Buyers seeking a stock-sound or silent setup should look at GFB’s recirculating BOV options instead.

VTA — Vent-to-Atmosphere

VTA BOVs vent compressed air from the intake tract directly to atmosphere on throttle lift rather than recirculating it back to the compressor inlet. This produces the characteristic BOV sound and eliminates any recirculation valve restriction in the intake path. On mass-airflow sensor (MAF) equipped vehicles, venting metered air to atmosphere before it reaches the engine can cause a brief lean-then-rich transient at idle following a lift event — this is a known characteristic of VTA on MAF-equipped vehicles and is typically well-managed on modern ECUs. If the Giulia/Stelvio QV is running a custom or modified tune, confirm VTA compatibility with your tuner.

Twin Kit — Both Turbos Covered

The Giulia and Stelvio Quadrifoglio use the 2.9L Ferrari-sourced twin-turbocharged V6 (bi-turbo) — two turbochargers, each with its own compressor outlet and recirculation valve. The T9416-2 includes two Whistling Trumpet BOV assemblies to replace both factory recirculation valves simultaneously. Replacing only one valve on a twin-turbo system leaves mismatched pressure release characteristics between the two turbos on throttle lift. Both must be replaced together for consistent boost response and sound — which is exactly what this twin kit provides.

GFB Quality

Go Fast Bits BOVs are precision-machined from billet aluminium with hardened internal components. GFB is one of the most established performance BOV manufacturers globally, with a strong reputation for consistent valve operation, durable sealing, and reliable boost hold at elevated boost pressures. The T9416 is a direct-fit application-specific valve designed for the Giulia/Stelvio QV compressor outlet diameter and mounting provision — no fabrication or adapter required.

Fitment

• Alfa Romeo Giulia Quadrifoglio — 2.9L Biturbo V6
• Alfa Romeo Stelvio Quadrifoglio — 2.9L Biturbo V6
• Quadrifoglio only — does not fit Giulia 2.0T or Stelvio 2.0T

Quadrifoglio 2.9L Biturbo V6 only. VTA design — produces audible sound; not a recirculating/silent option. Confirm VTA compatibility with your tuner on modified calibrations. Professional installation recommended. Both BOVs should be replaced simultaneously on a twin-turbo application.

Specifications

• Brand: Go Fast Bits (GFB)
• Part Number: T9416-2
• Model: Whistling Trumpet
• Type: VTA (Vent-to-Atmosphere)
• Quantity: Twin kit (2 BOVs)
• Engine: 2.9L Biturbo V6
• Weight: 2.2 lbs (kit)
• Application: Alfa Romeo Giulia QV / Stelvio QV