from the looks of that. It's tricking the ECU into supplying the rail with more fuel pressure. This will probably result in more fuel being delivered.
It's an interesting idea, as diesels work by using a constant amount of air and varying the fuel. If you push in more fuel than the manufacturer originally specified your going to see black smoke (at full throttle) and a little bit more power. 65-82? Probably not. but maybe a small increase.
Do diesels run a catalytic converter? Im not sure, but if they do, then it wouldnt last too long with that thing on your car.
Save up more and get a proper remap, don't trust generic ebay boxes that trick sensors.
Edit: also I wouldn't be surpised if it made the car idle too high as it'll just deliver a bit more fuel all the time. Also diesels do have cats, and the extra soot this causes isnt going to do it any favours.