Just checked my factory filters this past weekend and they are finally at the point where they need changing. Definitely will be getting a set of these filters!
They have the S Type in axle back though and with an h pipe it sounds really good. There are a few videos on youtube for the S550s that have an h pipe with an S Type axleback.
Since you have the non active exhaust I would get a set of axle backs since the stock non active mufflers can sound pretty tinny with a resonator delete imo