Hi,
Have sold my Z4, sob, but have kept the Juicebox back for some new lucky owner.
This really does makes a DRAMATIC difference to the car's power output in a very controllable way.
More information is here
http://www.burgertuning.com/jb4_pnp_...nce_tuner.html
It is remarkably easy to self-install, just follow the instructions for your car, essentially any BMW with an N54 twin turbo engine.
Please contact me for more information. Price should read £225
John