Haven't seen any discussion on this board regarding this upgrade. This is a fairly hot topic in the E90 N55 section.
Results so far on 91-octane pump gas show about 40 wheel horsepower bump with no change in boost pressure. Results on an ethanol mix with custom JB4 mapping by Terry are showing an extra 70 wheel horsepower at 6,000+ RPM.
Looks to be a very nice option for the $1,000 asking price. Supposedly will work on any N55 produced prior to July 2013.
Link to the product:
http://www.pureturbos.com/store/bmw-...o-upgrade.html