Hi, Ralph,
Welcome to Stangnet! I was in the Netherlands on vacation earlier this year. My wife's parents were born in Holland and we stayed with her family while there.
While we were in Holland, we visited a friend in Almere who owns two Shelby Mustangs - both are supercharged. One is an 07 GT500 with a roots style supercharger (like the Saleen, only different) and the other is an 09 Terlingua with a Paxton supercharger (identical to the Vortech supercharger). If you live anywhere near Almere, my friend would probably love to assist you. His name is Patrick and he is the president of Dutch Mustang club.
I have a Vortech V2 supercharger on my 07 Mustang GT. The lag is not noticable with steep gears (I have 4.10 rear end gears), but you may sense some lag with the factory gears (3.31). The Vortech superchargers are very durable and fuel economy isn't much different than stock - good news for someone paying 1.5+ Euros per litre for gasoline.
On a side note, our trip to Holland this year was my first. The people were wonderful, the food was great (except the herring), and we saw much of the country in a short time (from the North Sea in the west to Borger and Terborg in the east and just about everywhere in between). Only saw a few Mustangs on the road during our 2 weeks there, but they were nice ones.
If you have trouble finding shops in the Netherlands to do the work on your car, I would almost bet there are a few shops in Germany???