its recomended to pull 12"-15" of vacuume with the pump. It can pull more but you shouldnt with a wet sump. The header evac will only pull about 5". Power gains..... not to sure about the header evac, but the vacuume pump can pick you up some serious power. I have heard of 40+HP gains


1969 Charger R/T under construction
2014 Ram 3500 Cummins
2006 Corvette Z06
2015 Corvette Z06
2014 BMW M5