My conclusions comparing the two:
G56 stage 1 - deeper slightly less rorty sound due to larger diameter silencers, but requiring supplied bulky heat shields. Uses standard air cleaner element with less restrictive scoop.
MMC/AeroSport stage 1 - silencers with baffles give throatier sound and quite raucous when throttle blipped compared to originals. Little subjective difference at motorway speeds though. Easy fit to 2014 -> car, although I foud heat shields required spacing washers (not supplied). Complete new less restrictive S & S air cleaner kit included, looks the part and easy fit. Far better value for money being over £500 less, although some doubt about current availability.
