These work by boosting the pressure to the fuel injectors on diesels.
Boosts the fuel pressure (which is already incredibly high) in the common rail. Can also increase the pressure in the turbo.
I had one fitted to a Mondeo TDCi many years ago.
Have to say, it made a massive difference in performance without any noteable decrease in economy. - there can be more black sooty smoke as the overboosting sometimes leaves unburnt fuel in the cylinders.
I think the general concensus is they they arepretty goodin the SHORT term. In the long term, they can lead to fuel pump, injector or turbo premature failure.
I did a lot of research on this at the time, and without a doubt, the generally agreed best way toget this performance upgradeis to get the ECU re-programmed with a map which is then tuned to the
specific car. Generally costs about £400, but doesnt boost pressures which can lead to the aforementioned premature failure.
Aproffessionally applied custom map is definitely the safe way to go - the tuning boxes are pretty good, but not recommended if you intend to keep your car for a while!!!
--Oh and dont be conned into the idea that they programme to your specific model. If they re-programmed to your Specific Car, that would be another matter. every single engine/injector/fuel/turbo setup is different. a general map for the 1.5 Juke is hardly ideal for all 1.5 Jukes!
Andy