An injection molding system (10) includes a first mold half (20) and a second mold half (22), which forms a cavity (23) with the first mold half (20). A cavity intrusion element (34) is displaceable to extend within the cavity (23). A displacement mechanism (36) is coupled to the cavity intrusion element (34). A controller (38) is coupled to the displacement mechanism (36) and controls the intrusion depth (D) of the cavity intrusion element (34) during an injection molding process. A method of forming an article includes the pressurizing of the cavity (23) within a mold (14) via a gas. A material having a blowing agent is injected into the cavity (23). The gas pressure within the cavity (23) is released. The cavity intrusion element (34) is backed out from within the cavity (23). The material is cured.