Euro3 to euro4
I am a new member of this forum and am interested in buying my first own alfa 156. I am looking at buying one with euro3 norm in Germany and importing it into Slovenia. Since my country has higher taxes for vehicles with euro3 than euro4 norm, and I may well see restricted areas (town centers,..) for vehicles based on this cirteria in the near future, I am thinking about converting it to euro4. I am looking at an alfa 156 1.8 TS MY2003 (facelift with the giugiaro look). I noticed that this model can be found with euro4 norm but only if it was built in the second half of 2004.
My questions are:
Is it possible to convert the alfa I am looking at from euro3 to euro4?
If yes, what is needed for such of a conversion? I investegated if the later models have different exhaust systems or some other mechanical tweaks to the enigne to make it euro4 but I found none. Is it therefore only an ECU flash that is required for a conversion?
And is it possible by converting the car to run on LPG (or gas) to also convert it to be an euro4 car?