I installed a GReddy axle back exhaust shortly after buying my xB and have really enjoyed the sound. Recently I've developed an exhaust leak at the coupler and I've been meaning to repair it but it seems the louder it gets the faster it gets. Noticably faster. I'm not sure if this is because of the reduced back pressure or the fact I've got 3900 miles on it now and it's starting to break in. If it's the reduced back pressure I may just replace rather than repair it. Any thoughts?

sounds like you need to replace the donut gasket around that joint...

... GReddy axle back exhaust... developed an exhaust leak at the coupler... Any thoughts?

Was the old exhaust gasket re-used, or preferably a new one installed?
It is a white ceramic doughnut, part no. 90917-06082, $13.55.