Tuning box - many available, they do make a difference, try to get one from a well known supplier. Or preferably...........................
Remap - Take advice, do your research and make sure you understand what you want and what you are buying. There are a couple of companies out there that come with a good reputation and also a couple of individuals who do good work too.
De cat - yes, get your garage or someone with a welder to cut it out and replace with a straight length of pipe. Does not affect MOT and makes a difference to the way it drives.
De EGR - if you have Bosch, then take it off, or blank it, or just disconnect the plug.
Don't think about injectors. They are very difficult to get hold of, expensive and difficult to calibrate properly
To go further you will need to intercool. Again do your research on what you want to achieve and how you are going to go about it.
There is a wealth of information out there and loads of people who will help with advice, experience etc. Problem is, very little is Berlingo specific and it is scattered all over the Web. Just take your time collating it.
Hope this gives you a starting point and an idea of what to do next. This is the route that I wanted to take, but having the Siemens system, I am unable.
If I can help further, let me know.
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