Some of the old Yamaha 750 dirt trackers had a mid-pipe resonator like that, so I'd guess it probably does something good, maybe adds some torque at a certain rpm range. I'm with you, though, those headers would look MUCH better if they were one smooth pipe bend, not a hundred little pieces welded together.I saw those as well when I was looking for an exhaust for my 350. But I didn't want to be the first to buy them, lol. Not to sure if I like the resonators, and the way the headers are a bunch of little welded up pieces. I don't think it looks quite right. For me anyway.