I've never heard the downpipes in person. I just watched a few videos demonstrating the sound, but it's hard to judge through computer speakers. Are they really loud and obnoxious? I don't want to sound ricey.
Also, I emailed OSS for a quote today too. I would do the full interior blackouts to match all my flat black accents.
I was basically thinking either OSS headlights and M3 side skirts or Cobb. Seems like you guys have said mostly the same stuff. I also want to upgrade the OEM wheels, but that's more than 1000. My third option would be to save up a little more and do that.