A stretch blow molding system (200) is provided. The stretch blow molding system (200) includes a cylinder (201) with a movable stretch rod (202). The stretch blow molding system (200) further includes a proportional pre -blowing valve (204) including a first fluid port (204a) in fluid communication with a first pressurized fluid source (244) at a first pressure and a second fluid port (204b) in fluid communication with the cylinder (201) and selectively in fluid communication with the first fluid port (204a). The stretch blow molding system (200) further comprises a blowing valve (214) including a first fluid port (214a) in fluid communication with a second pressurized fluid source (247) at a second pressure, higher than the first pressure, and a second fluid port (214b) in fluid communication with the cylinder (201) and selectively in fluid communication with the first fluid port (214a).