embodiments the hole may be molded into the second component or machined after molding as illustrated at block 116 the second component is disposed in a desired position relative to the first component as illustrated at block 118 in an exemplary embodiment where the first component is a first component of a spoiler and the second component is a second component of a spoiler the first component may be superposed over the second component to form upper and lower portions of the spoiler respectively the cap is assembled over the hole as illustrated at block 120 in an exemplary embodiment the cap is positioned in a location that would be hidden from view after assembly e g to preserve a desired aesthetic effect the cap is welded to the first component via the hole as illustrated at block 122 this may include friction welding or vibration welding as illustrated at block 124 however other welding techniques and or other tools for applying heat and pressure may also be used as may be seen the present disclosure provides a system and method for joining via welding plastic components having different material compositions which are otherwise not weld compatible advantageously such systems and methods may be used to assemble a two piece spoiler having an upper portion with a different material composition than a.