There is a lot of talk in the forums about X5M tuning options, but very little on the N55 3.0L engine.
I know there is a huge lack of performance options for the car, but I was hoping for more info on the topic. Especially any feedback on the existing products out there!
Here's a short list (US Based) of what I've found in terms of tuning options. Pricing not mentioned, as it's not terribly important to me at the moment...
Piggyback system:
Burger Motorsports -
N55 Stage 1
Reflashes (Often you have to ship your ECU, or else find an authorized dealer):
Active Autowerkes
Can't confirm N55 compatibility, but will email them eventually
ESS Tuning
ESS Tuning Stage 1, works for N55 they claim
Dinan
Hey it's on sale... 
Cobb Tuning had started development for the N55 a couple years ago, but stopped. I'm not surprised, since it's Cobb and they can be really flaky when it comes to product development and timeliness. Though I would love an accessport for my car.
(There is an old thread on an X6 as a beta user I found.) An email to cobb and FB post, said pretty much no more...
What else is out there?
Who has one of the above, and what are your impressions?
I think ultimately I want a reflash, as I've found in the past that piggybacks are not the "smoothest," systems in overall drive-ability, but they do make power. I think it's the transition from closed to open loop that is a problem for them? Where as a reflash doesn't usually suffer that, when done right.