Forge Motorsport manufacture a wide range of tuning and accessory products. Probably most famous for their billet aluminium, diverter valves which operate with a 10mm larger diameter port than the standard item. This increased area produces both quicker throttle response and higher clamping load to maintain boost pressure more reliably. They are also piston operated and suffer none of the failures associated with diaphragm type dump valves.

Also from Forge and LMA we have Manual Boost Contollers which are either adjustable from under the bonnet or in car depending on what your requirements are.