Best place to get m235 rear diffuser for 228i dual exchaust.

Whats the best / cheapest place to get 235 diffusor for 228 muffler delete dual exhaust?



Is OEM the cheapest option?



I found this at a bmw dealer. Am I looking at the correct part? Part # 3?



http://ift.tt/1Dgr2bo



Do I need anything additional with this? Like extra rivets or something?



Thank You,



Roman