There is a uk section of this forum with a number of guys running jb4 (myself included).
Juiceduptuning.co.uk is a UK distributor for the jb4 and numerous other products, checkout the website.
You just need to work out whether you have an N54 (twin turbo) or N55 engine (twin power turbo) - 2009 was the year it changed...
2008 E90 335i LCI M Sport / Manual / Black / Red Leather / Avon ZZ3 / VMR710
Mods: JB4 / BMS DCI /AR Design DPs / ETS FMIC / Water Meth Injection / BMS Chargepipe / BMS OCC / Cool Carbon Brake Pads / Rob Beck PCV Valve / Forge Diverter Valves
Wish List: LSD / Bastuck Quads / Birds Suspension / M3 Arms