i use OEM 400ex mufflers on alot of machines. They are still semi cheap flow ok and don't make a lot of noise. If you want aluminum stuff i just use take off OEM dirt bike mufflers. Those guys chase every bit of HP and for what at full throttle. I scored a KX450F one of a 2020 for $65, welded up a mid pipe and bam new nice muffler looks cool sounds good done.