you dont really have to worry bout that. even when you sell the car, you can just weld the old mufflers back on. most people wont even bother looking down there unless of course your muffler has a hole in it or something.
Current: 2013 F10 M5 & 2013 GLK350
997.1 GT3RS (gone)
2009 WRX STI (gone)
e92 M3 (gone)