http://www.chipexpress.com/products/3487/

£395 Pay a little more and go for a proper tune. Do Chip Express have any rolling road graphs or just claims? The benefits of plug and play are limited and the limitations well publicised on the forum. Reversion back to standard on a proper tume doesn't even involve opening the bonnet. Tuning has advanced a long way too, I used to have an Autologic Tune that had been produced for a 'stock standard' vehicle, eventually that too started giving me issues with overboost due to further vehicle enhancements. The tunes nowadays can take into consideration different parameters and adjust accordingly.

Fron Chip Express....."To fine-tune your system simply remove the rear end of the module where you can make small incremental adjustments above or below the supplied setting using the power selector within, easy to do and fully explained in instructions supplied."

Undoubtedly this will be a variable potentiometer or in simple terms the resistor Martin refers to in his post below.

Tucked away in one of the threads and a couple of years old but for the price difference get something well proven with loads of positive feedback, 'pm' or phone Gary at Alive or Pete at Bell Auto Services either way you would not be disappointed.

Martin wrote:

A tuning box can never match a true remap. Tuning boxes fool the ECU and engine into operating different to what each other "thinks" - i.e. it's a box which modifies signals going both ways to trick them.

At its crudest, this is simply a resistor to lower the rail pressure signal to the ECU, so the ECU raises it as it doesn't match its set point. Higher diesel pressure means more diesel injected per firing, but it takes NO account of the other engine parameters required to determine if this is a good idea or not.

These parameters can include but are not limited to fuel temperature, boost pressure, engine temperature, driver driver, inlet air temperature, charge temperature, air flow, gearbox gear, EGR state... [etc]

A remap does increase fuelling, but by altering the maps which are read as a result of looking at all these other parameters FIRST. A tuning box lets the ECU work out where it should be operating, and then just bungs some on top, and lies in return.