Abstract: Poultry processing systems, piston pump assemblies, and modular pump bases along with related methods are described herein. The poultry processing systems may include injection stations that allow for adjustment of an approach angle relative to a bird in a bird support aligned with the injection stations. The poultry processing systems may include piston pump assemblies using dosage pucks to provide accurate control over the volume of each bolus of liquid delivered with each activation of the piston pump assemblies. The poultry processing systems may include pumping bases and pump identification systems to allow for easy and quick changeover of pumps associated with the poultry processing systems.