After some searching I couldn't find much about this kit in the UK so here we go.
Having made the schoolboy error of buying a 2010 E91 only then to find the ECU is encrypted and that the Bluefin unit I used on my previous car (2.0 focus diesel - responded very well to it) was no use I could only see 2 options:
330D or BMW Performance Power Kit.
The head won, helped by a significant uplift in annual mileage so off to Snow's in Portsmouth it was to get what on paper is a modest upgrade considering the parts fitted(ECU, intercooler, engine fan).
First up - Cost. 2hrs labour (fixed price) + parts came to about £1100 - not cheap but looks cheaper than the BMW web site says.
Fitting: - The dealer had problems programming the new ECU so lets just say it was a good job that it is a fixed price job. They did keep me up to date with what was going on so no complaints about customer service.
Economy - Three weeks since the upgrade and now about 6-7 mpg better than before.
Performance - Wow. The car felt flat before and when the dealer said it felt better on a post fit test drive he wasn't lying. At idle it seems a bit less clattery but this is not what the kit is about. Mid range onwards it is now the car that I wanted. As soon as you leave a 30 zone you notice the difference, pulls strongly across the rev range and keeps going, resulting in the need to watch the speedo a bit more closely. Engine is much more flexible and better in every single way. Not sure what it is putting out - but definitely feels so much better and more powerful than official figures. Previously my old car may just embarrass the Beemer - not a hope in hell any more.
Sumary: If you have a 2009 or earlier car - use a third party remap. If you have a newer car this is highly recommended - you will never get your money back but the smile more than makes up for it.