The articles under consideration have been identified as Ningbo Siming exhaust tips (CD539 and E2SC). The exhaust tips are a decorative trim piece for the rear of an automobile or truck. According to your documentation, each tip is a piece of chrome plated trim made predominately of metal with a plastic cuff. The tips are not a part of the muffler or exhaust system, but merely attached to the rear of the vehicle for decorative purposes.
[1] Please importantly note that only the relevant portion of the related is displayed above. You may refer to the said customs ruling for the entire ruling explanation.
[1]. https://rulings.cbp.gov/ruling/N301640