This upgrade increases shot count by enabling the rifle to shoot standard velocities at a lower regulator pressure. For higher powered shots the regulator will need to be tuned at a higher pressure lowering the shot count. Example: A .25 MK2 without the upgrade is shooting 900 fps with 34gr with reg at 145 bar, with the New Power Plenum this would be attainable at approx 110 bar. For higher powers the regulator will need to be set higher. Example: With the Power Plenum at 145 reg pressure you can expect high 900's FPS. Rifle will need to be shipped to SPAW for install, tuning to customers power specs is included in the price. Customer is responsible for return shipping if it exceeds shipping at check out.