Thanks,
Would this cause any problems in the long term?
And what does an ECU remap actually do ?
A sympathetic remap should not cause any problems at all either in the short or long term. What it does is effectively 'take up the slack' built in by car manfacturers. Such 'slack' in used for one or two purposes, by car makers.
Firstly, the makers need to maintain a marketable position for their petrol models. It's embarrasing for them that a diesel 1.9 would out pace a larger engined petrol one.
Secondly - the cars are sold across Europe, or even across the world. Fuel quality is questionable in some regions. The manufacturer has to ensure that the car will remain economic for them to maintain within warranty.
A good ECu remap will work very well.
Firstly, the fuelling will be adjusted according to recorded sense data in the ECU for your car. The purpose of this is to smooth the torque delivery. This alone, can make a car feel livlier. After this, they will look to increase turbo boost pressure, and accompany it with increases in fuel delivery to make use of the available air. Often the maximum diesel fuel rail pressure will be allowed lower down the rev range. THis helps combustion efficiency, a good tuner will not exceed the max rail pressure.
I doubt that you'll encounter any issues at all. Just be aware that if you have your car remapped, thus taking up some of the 'slack' you need to be considerate when driving it.
Don't, for example, boot it brutally from stone cold.
And do accept that it will run hotter than normal. So give it a minute or two to cool off after working it very hard. This applies to any car really. petrol/diesel/ tuned or standard.
A remapped diesel can be a joy to drive, with midrange muscle that you'd never imagine possible this side of a Boxster E.
It is a win win situation, just be a little sympathetic to the engine before taking absolute liberties.