Allow me to not answer your question while giving several facts. I don't know where to tell you to go for the exhaust work, but I would advise the following:
Keep with close to OEM parts if possible. Further, I would reccomend NOT eliminating the mid muffler. They do A LOT to reduce noise, and more importantly the resonation of the exhaust inside the car. I had an exhaust which replaced the mid muffler with a straight, mild dampening muffler on the Golf, and it would give you a headache in certain rev ranges. I remember finally deciding to take it back off of the car following a trip up Monteagle Mountain.

That being said, you should be safe with any shop, just make sure of what they are putting on there. VWs don't like universal Catalytic converters, but I don't know that the mid-muffler is a big deal outside of just making sure that you leave it on there.
Just my two cents.
