The Splitter, a Recirculation and Blow Off Valve



We recommend servicing your valve every 3 years, or 20,000 miles, whichever comes sooner

The Splitter is a truly remarkable valve that gives a combination of blow off and recirculation valve operation, all at the same time, and has been specifically designed for the many turbo engined applications that operate metered airflow management systems. This means you get all the noise of the blow off valve whilst retaining the compatibility with the recirculation requirements of the engine management system. As a bonus we also offer the ability to convert the valve to recirculation only mode for those times when stealth running is required.

This valve uses a Brass piston which utilises new sealing technology along with a variable spring preload, incorporating a ratchet type top adjuster that will allow for the positive and precise adjustment to match the valve to your engine. This is achieved by using a unique single, conical, progressive rate spring, that can allow for the retention of boost pressure over a wide adjustment range. This unique spring design also allows for unrestricted piston travel and flow volume regardless of the amount of pre-load adjustment added to the spring.

Other manufacturers' valves use cylindrical springs with adjustable pre-load, which often experience restricted piston travel and a reduction in flow volume. When we say our products are Engineered For Performance, it's not a catchy sales phrase, it's the truth. and we prove it with every product we manufacture.

Note: This valve requires installing the opposite way to the original Bosch Valve. This means that the side pipe is fitted into the Turbo Intake Hose, and the base pipe connects to the hose that runs to the boost side of the turbo.


In The Box:
1 x Valve Blanking Cap
1 x Instruction Booklet
1 x Forge Sticker

If you are unsure if this product is suitable for your application, please contact us. 

The valve has a port size of 25mm





To service this valve, access the valve piston by removing the 3 cap screws at the base of the valve and simply clean the piston chamber using brake cleaner or similar cleaning fluid before installing the new spring and piston. Please observe the correct spring and piston orientation when installing the serviceable parts, as seen in the attached drawing.


Adjustment guide.

First turn the valve adjustment knob all the way down in the anti-clockwise direction, which will adjust the spring it to its lowest tension. Then turn the valve adjustment knob in the clockwise direction to the appropriate tension level, as set out below.

  • Standard engine – 16 clicks.
  • Stage 1 remap – 21 clicks.
  • Stage 2 remap – 25 clicks.

These adjustment recommendations are a general guide and you may find that your engine requires fine tuning by 1 or 2 clicks in either direction to achieve optimum performance.

There will be no significant performance benefit adjusting the valve over 30 clicks as the spring will have reached its maximum operating tension.



  • Audi
    • A3 > 1.8T
    • A4 > 1.8T (B5,B6 Models)
    • A6 > 1.8T (B5,B6 Models)
    • S3 > 1.8T (8L Chassis)
    • TT > Mk1 > 150/180BHP
    • TT > Mk1 > 210/225BHP
  • Seat
    • Ibiza > Mk2 (6K2) 1999-2002 > Petrol
    • Ibiza > Mk3 (6L) 2002-2008 > Petrol
    • Leon > Mk1 1998-2005 > Cupra 1.8T
    • Leon > Mk1 1998-2005 > Cupra R 1.8T
  • Skoda
    • Octavia > 1.8T
  • Volkswagen
    • Beetle > 1.8T
    • Golf > MK4 > 1.8T
    • Passat > 1.8T
    • Polo > 1.8T