I have a 07 550i and I looking to buy a mtech rear bumper single side diffuser and maybe quad the rear later. I figure Ill go this route bc I could just remove the single side and put the quad diffuser on when I quad my exhaust. Well I called a few well known places and they all said I would not be able to put on a quad diffuser bc it won't fit and I would have to cut the single diffuser to make it a quad. If this is true then why do I see tons of e60's online with mtech rear bumpers and quad diffusers and or tons of quad diffusers for sale online. Is there a specific mtech rear that I should get or did I get some not so true info?

 

I believe some are purchasing and retrofitting a oem M5 quad bumper on to their e60. My understanding is that it has other connection locations and fitment that needs to be finessed to fit a standard e60. The other option I have seen on here is cutting the single Mtech. I suppose there are other manufactures out there making rear diffusers that may be quad, but I haven't looked into that.

Important to note that the e60 has limited room on the passenger side for a 2nd muffler. Most just run a second tip. Other have relocated the battery well and made room for a new muffler. Its not as easy as buying a second muffler and slapping it on.