18/02/2026
Optimal Performance with GFB’s Custom Weld-On DV and BOV’s
GFB has a small range of their Diverter and Blow Off Valves that are designed for custom weld-on applications. These products are almost identical to their usual counterparts, but with some alterations to allow for easy welding onto stainless or aluminium piping.
GFB utilises their V-band mounting system for these products, but you will need to purchase the appropriate weld-on fl**ge and outlet fitting to suit your specific application. This saves you paying more for extra adaptors that you don’t end up using.
T9019 - Custom Weld-on Respons TMS
GFB’s custom weld-on Response TMS (T9019) may look like just another dual-port blow-off valve, but its actually much more than that. It features GFB’s venting bias adjustment system which allows you to precisely control how much air vents from each of the two outlets.
This system allows you to adjust how loud the blow off sound is, without causing stalling, backfiring or any other BOV-related issues, even on a car with a sensitive airflow meter (MAF). Adjustable from full recirculation with silent factory operation to maximum noise by venting to atmosphere, or set it ANYWHERE in between to your own personal preference.
This product isn’t just a noise-maker, it also offers better throttle response, faster boost recovery on gearshift and unlimited boost-holding* for maximum performance.
T9119 - Custom Weld-on Mach 2 Recirculation Valve
GFB’s custom weld-on Mach 2 TMS (T9119) is perfect for those who want simple boost performance WITHOUT the noise. The Mach 2 is configured as a 100% recirculating valve as a direct factory replacement, but with the use of GFB’s TMS technology returns the engine to peak boost up to 30% faster than a factory diverter valve when shifting gears.
Factory bypass valves typically have two main shortcomings- they are often designed to blow open above a certain pressure to protect the engine, and that they are not optimised for throttle response. The Mach 2 range solves both issues. With its pressure-balanced design, it can effectively hold almost unlimited boost and the TMS technology ensure maximum throttle response.
T9219 - Custom Weld-on Hybrid TMS Dual Outlet Valve
GFB’s custom weld-on Hybrid TMS (T9219) is a refined weld- on version of their original Hybrid valve designed in 1999, which pioneered the dual port design market.
By “staging” the two venting outlets, at low valve lifts most of the air is recirculated. As the car is driven harder, the valve opens further and more of the atmosphere venting port is exposed for a louder sound. The use of TMS technology also provides up to 30% faster boost recovery on gearshift when compared to factory valves.
As a benefit, this system makes it possible to use these valves on cars with sensitive airflow meters (MAF) that often suffer issues such as backfiring and/or stalling, whilst still achieving the signature blow-off sound.
GFB’s T9219 can be paired with their hose blanking plugs that allow the valve to be configured for full recirculation venting, 50/50 (atmosphere / recirculation), or full atmosphere venting.
T9519 - Custom Weld-on Deceptor Pro II
GFB’s custom weld-on Deceptor Pro II (T9519) gives you the ability to control the sound of the BOV from inside the cabin.
The Deceptor Pro II takes the ‘Respons’ concept even further; with a compact design, new bore finishing process and revised porting for a lifetime of reliable operation with optimised flow and venting bias.
The sleek, compact in-car BOV volume controller allows for proportional venting bias/volume control - from silent to loud or anywhere in between at the turn of a dial.
The Deceptor Pro II also utilises the same TMS technology for faster boost recovery from gearshifts, and increased throttle response.