Any aftermarket chrome exhaust will "Blue" on the bends as they are single skinned against the original double skinned.
I have fitted a Marxshall to a 550 and the fit and initial finish was good, as was the exhaust note---in fact under the current rules a dubious MOT pass--- but had to modify the silencer hanger as it varies depending on which frame its going on----By the way DO NOT cut aff the rear footrest hangers until after you have decided on an exhaust as a lot of them mount there!