Muffler question re: Ryobi/Zenoah saws

[drfeelgood]

Does anyone know if the mufflers available online(part # 308539001) for the Ryobi 10532/Zenoah GZ400 are empty can/pre-emissions versions versus the ones on newer Ryobi 3714/MTD 38-40cc saws that are heavy and choked up with a cat. Am working on easiest way to "muffler mod" and port some of these without cutting open, unclogging and JB Welding the newer mufflers.