The AVC-R is a digital boost controller that allows the user to modify the boost pressure level on turbocharged vehicles. The AVC-R also uses a highly durable, fast action solenoid valve to physically control the boost . The valve movement (Boost Duty Cycle) can also be modified. Raising the duty cycle increases boost response, while lowering the duty cycle will slow boost response. This feature allows boost response adjustment for varying turbo sizes. Since larger turbos take longer to spool up ( bad low end response) the duty cycle should be raised under lower RPM's for better response. The opposite should be done for smaller turbo's ( excellent low - mid range response, but limited top end power.) A'PEXi engineers address this issue by including extra menus for RPM based boost control. Drag racers may want to utilize the Gear based boost control function. Aside from the basic functions above, the AVC-R has a Start Duty Setting (allows the boost to momentarily overshoot according to gear).