A method of injection molding a thinwall part at a substantially constant pressure, the method comprising: operating an injection system to advance molten thermoplastic material into a mold cavity, wherein the mold cavity has an L/T ratio of 100 or greater, and operating at an increasing power (0-t1) until a predetermined injection pressure is reached; and wherein the method further comprises: adjusting a filling pressure profile to cause the power of the injection system to peak within a first 30% of the mold cavity being filled; and reducing the power (t1-100) until the mold cavity is substantially filled with thermoplastic material to maintain a substantially constant injection pressure of less than 10,000 psi (703 kilograms force per square centimeter) for thermoplastic material chosen from the group of polypropylene, nylon, polycarbonate, polystyrene, styrene acrylonitrile, low-density polyethylene, high-density polyethylene, thermoplastic elastomer, polyvinylidene fluoride, polytrimethylene terephthalate, polybutylene terephthalate, polylactic acid, poly(ethylene furanoate) polyhydroxyalkanoate, and polyethylene furanoate, to maintain a substantially constant injection pressure of less than 8,000 psi (562 kilograms force per square centimeter) for acrylonitrile butadiene styrene, to maintain a substantially constant injection pressure of less than 5,800 psi (408 kilograms force per square centimeter) for polyethylene terephthalate, or to maintain a substantially constant injection pressure of less than 7,000 psi (492 kilograms force per square centimeter) for acetal copolymer. operating an injection system to advance molten thermoplastic material into a mold cavity, wherein the mold cavity has an L/T ratio of 100 or greater, and operating at an increasing power (0-t1) until a predetermined injection pressure is reached; and wherein the method further comprises: adjusting a filling pressure profile to cause the power of the injection system to peak within a first 30% of the mold cavity being filled; and reducing the power (t1-100) until the mold cavity is substantially filled with thermoplastic material to maintain a substantially constant injection pressure of less than 10,000 psi (703 kilograms force per square centimeter) for thermoplastic material chosen from the group of polypropylene, nylon, polycarbonate, polystyrene, styrene acrylonitrile, low-density polyethylene, high-density polyethylene, thermoplastic elastomer, polyvinylidene fluoride, polytrimethylene terephthalate, polybutylene terephthalate, polylactic acid, poly(ethylene furanoate) polyhydroxyalkanoate, and polyethylene furanoate, to maintain a substantially constant injection pressure of less than 8,000 psi (562 kilograms force per square centimeter) for acrylonitrile butadiene styrene, to maintain a substantially constant injection pressure of less than 5,800 psi (408 kilograms force per square centimeter) for polyethylene terephthalate, or to maintain a substantially constant injection pressure of less than 7,000 psi (492 kilograms force per square centimeter) for acetal copolymer. adjusting a filling pressure profile to cause the power of the injection system to peak within a first 30% of the mold cavity being filled; and reducing the power (t1-100) until the mold cavity is substantially filled with thermoplastic material to maintain a substantially constant injection pressure of less than 10,000 psi (703 kilograms force per square centimeter) for thermoplastic material chosen from the group of polypropylene, nylon, polycarbonate, polystyrene, styrene acrylonitrile, low-density polyethylene, high-density polyethylene, thermoplastic elastomer, polyvinylidene fluoride, polytrimethylene terephthalate, polybutylene terephthalate, polylactic acid, poly(ethylene furanoate) polyhydroxyalkanoate, and polyethylene furanoate, to maintain a substantially constant injection pressure of less than 8,000 psi (562 kilograms force per square centimeter) for acrylonitrile butadiene styrene, to maintain a substantially constant injection pressure of less than 5,800 psi (408 kilograms force per square centimeter) for polyethylene terephthalate, or to maintain a substantially constant injection pressure of less than 7,000 psi (492 kilograms force per square centimeter) for acetal copolymer.