As a rule of thumb you can get pipes to interchange from cb500 to cb550 but you'll need to play around with the rear footrest hangar and also be wary of having a stop for the centre stand which can hit the chain if the required stops aren't in the right place on the exhaust brackets / system. In other words be prepared to spend time drilling, cutting, and bending steel or alloy if interchanging exhausts from cb500 to cb550. I have always chosen exhaust systems for these bikes based on what I can get cheap. Currently I have a laser 4 into 1 fitted, not too loud unless you really use the throttle, then it's pretty anti social.