I would like to recommend a top BMW performance tuner. For remaps and chip tuning.
I have just had my car chipped today and what can I say. What a great job Jason from BW Chip Tune has done
They can remap and chip any BMW and are also BMW specialists (servicing and repairs)
There website is: http://www.bwchiptune.co.uk/
Jason spent 3/4 hours with my car and made a custom tune to my specification. The power gains are impressive. Cost me £175 (cheap). While worth the 120 mile trip down to him.
He's been in the game for a long time and really knows his stuff when it comes to BMW tuning. Showed me exactly what he was doing very impressed. He tuned one of the fastest M5's in the country.
Here's Jason's X5 in action:
I know Steve23002 has also had this BMW chipped by BW Chip Tune and tell everyone how good they are.
I would recommend BW Chip Tune to anyone.