was £183.59

£149.99

• Dual-function: blow-off and recirculation
• Brass piston with advanced sealing
• Adjustable spring preload (ratchet top adjuster)
• Conical progressive-rate spring for consistent boost retention
• Full piston travel and maximum flow at all preload settings
• Serviceable design
• Designed, machined, and hand-assembled in the UK
• Lifetime warranty

The Splitter valve combines blow-off acoustics with full recirculation compatibility for turbocharged engines using metered airflow systems. Maintains ECU stability while delivering venting performance. Convertible to recirculation-only mode. Utilizes a brass piston with precision sealing and a single conical progressive spring, ensuring stable boost control across a wide adjustment range without restricting piston travel or flow—unlike conventional cylindrical spring designs.

Installation Note: Reverse orientation vs. OEM Bosch valve. Side port → turbo intake hose; base port → boost-side hose.

Servicing - 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 drawing below.

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.