@Frankie
The 660 has been worked on by a guy in the UK and has a dual port muffler. It is torquier than a standard 660 hence why I changed up the sprocket.
Just recently I have been having a lot of trouble with the chains. Never had a problem in the UK, just went to the store and asked for a 30inch chain for a Sugihara bar for the 660. Worked every time.
Here in Norway, it seems to be a problem as a couple of the places close by haven't even heard of a 660, or a 200t for that matter. They only know what a Stihl Catalogue tells them.
When ordering carb parts I have had to get them to open the technical diagrams for the part numbers or near as dammit, they will order the wrong thing.
I tried to get a new 12 bar for my 200t last year. Once I got them to realise that the 200t was actually an older model, they tried to sell me a bar and chain combo of 15 inch that looked like it was suited to fit a ms 180 or similar.
Off course, but could just be the local shop but that is why I tend to put in bulk orders from the UK these days, much cheaper and they deliver the correct stuff I need.