We offer a fantastic tune for the X5M and X6M as well:
Peak gains are normally 70-100hp and 90-130 ft/lbs (depends on octane).
Have a look at the dyno here:
http://www.xbimmers.com/forums/showthread.php?t=763955
Comes with the Flashing cable which you can keep - flash to stock + read and clear fault codes. Takes only ten minutes to flash the file in
Cheaper than all of the alternatives above.
You can find some reviews of our M3 software here - (uses the same cable and process):
http://www.m3post.com/forums/showthread.php?t=784717