Abstract: A side injection plural component spray gun having one or more injector assemblies mounted for injecting a catalyst into a main component at the most forward position of the spray gun. In one embodiment, the injecting assembly has an injection jet connected to the air path for injecting a catalyst into the air stream just before it exits a port for shaping the main component into a fan shaped pattern. The injection jet is constructed to minimize adverse effects on the air stream for shaping the spray pattern. In a second embodiment, dual injection assemblies inject catalyst for delivery through both shaping air ports on either side of the fan shaped pattern of the main component or allows injection of a third component. These embodiments minimize the build-up of catalyst on the walls and passageways of the spray gun minimizing the need for maintenance of the gun and preventing clogging and corrosion of passageways.