So looks like the Eissenman exhaust fits fine in my 550i. Just not with the M5 F10 rear diffuser. F10 M5 Diffuser tips outlets sit inboard by about 2" and my installer/shop are having major problems because the Eissenman Race exhaust is large and the passenger side just won't align to the outlets. No cutting or adjusting seems to work other than major modifications to the rear body/frame/wheel well. So its back to my OEM M sport diffuser unless I want to now swap out exhaust to something smaller or that definitely fits (OEM M5 cans - that probably would have been less expensive than my Eissenmans!) LOL
More to come later when I get an update in the AM.
'12 F10 550i (Dinan Stage 5/Intercoolers, CF Intake, Brace, Shockware, H&R Springs, Eisenmann Race Exhaust, CF rear difuser, Giovanni "Lindo" Graphite 20")
'10 e71 X6 35iDrive SAV (Space Gray) - Gone
'06 e85 Z4 M Roadster (Black Metallic) -Gone
'08 e92 M3 coupe (Sparkling Graphite) -Gone