My Moto GP can that I have on at the moment is sold as road legal, has the proper markings too, but is loud with the baffle in, and stupidly loud with the baffle out.
Got an MOT advisory once but he hadn't seen the markings.
I've saved the website page on my phone now in case anyone questions it.
I've tried it without the baffle before but suddenly became "that" person that everyone looks round at as you approach them. Way too much attention for my liking, plus the noise can get a bit tedious too.