I'm going to confirm this tomorrow but I believe that the Powergate that I can supply will work on a E91 318D. If this is the case then I think you will find it alot better than the blufin. The maps for the powergate are tailored for that particular vehicle i.e NOT GENERIC.
You buy the unit and upload your original map from your car to the unit. Then this data you send off and within an hour (usually) you get 2 modified maps back of you choice. Upload these to the unit and connect to car and you can change between the maps to your hearts content. Also the powergate doubles as as basic diagnostic tool.
Price for this is £350+£15P&P
Group buy deals can be organised also and if I was to get an order of atleast 10 units then the price will be reduced to £310+£15P&P Saving of £40!
As I say, I will confirm for your vehicle tomorrow.
Email me direct at info@APTuning.co.uk