I don't know too much about the euros, but if you have a catalytic converter, get rid of it; if you have an EGR, disconnect it. Non turbos are quite sluggish compared to turbos, there's not much you can do. Adding a turbo is not a good idea, since the non turbos have different specs
afaik. However, it's always a good idea to take care of the basic maintenance first, like changing
all filters. Spend some time reading this forum, use the search button, etc.
Please don't sell it, though, just because it's slow, you have a great car there! Congratulations and welcome to the diesel crowd.