I agree with the others. Fairly straight forward. The instructions are good. Just take your time, and don't force anything. Everything comes apart and goes together easily if you have all the screws out, and everything lined up correctly. Snapping the clips on the ECU can be a little hard if you have big hands.
Pay particular attention to the orientation of the connectors inside the ECU. They are not marked well, and can be inserted backwards. A touch of magic marker, or a "before" photo could save you some time.
2010 E90 335i Xdrive| Titanium Silver Metallic | Black Leather | Premium, Sport, Nav, Cold | Steptronic | matte black grilles | Cyba scoops | pinstripes | Rear Fog Mod | Clear Reflectors | WeissLicht AE |More to come...|