Things like this are best left alone unless the car will be mapped to use it, If a boost controller's what you want, get a custom remap with boost controller mapped in at the same time.
 
if you're car is remapped then boost has been increased already.

Also, mechanical boost controllers increase boost regardless of RPM/engine load. Your ECU already does everything for you. The boost controller you showed is best used on cars that have primitive ECU's.

Also, if you increase the boost enough to notice an increase in power, the ECU will also notice it and put the car in limp mode as the actual boost will be more than the requested boost.