Boostvalve is placed inline between the turbo compressor and the N75 solenoid. Works as a manual boost controller to decrease spool-up and manually preset max boost. Can be used on stock or chipped cars. (Boostvalve kit used: VW-BV). This is the setup you want to use if your car is running fine, and currently do not have any issues with error codes, limp mode or excessive spike.  If your chip or N75-J valve is causing any problems you want to hookup the Boostvalve as shown on the "Over Boost Solution" page.