To increase power!A small Boost increase will increase power! More boost means a more efficient intercooler to drop ACT's! I didn't want a smart **** post, I asked for answers. I'm guessing you don't know them so go be smart somewhere else!
Only if you have the fueling to match!
A tuning box is a pretty naff tuning toy, it's only suitable as a cheap way to get a bit more power from a standard engine, and works well, but is in no way a tool to use for major power increase, as it's very crude!
Diesels run lean as standard from the factory for emmisions, altering the amount of fuel going in ie richening it give more power but more smoke usually.
Increasing boost will not work atall as the ECU has preset overboost settings and the car will go in to limp mode.
Don't go messing with things u don't understand, I've been there and done it.
Also the standard ECU is set up for stock intercooler, I have a feeling the new one on mine is less re-strictive and therefore running slightly higherboost after int, and the ECU don't like it atall, makes motorway driving impossible at speed as it goes in to limp mode.