MZ/MuZ Riders

I know there are plenty of shops in the US that specialize in doing machine work on Raptor 660 top ends but I was wondering if anyone could recommend a shop that has done good work for them on their Skorpion. I want to do as much as I can to mine but keep the motor reliable. Any suggestions would be appreciated.

Here's one of the shops that I found but I don't know anything about them. The last two options they offer is the type of work that I'm looking to get done. Thanks
http://advmachining.com/Raptor.html

since both the Raptor and the XTZ have the same 5-valve head technically, anybody doing Raptors can do the XTZ as well.
Obviousl choices for motorcycle use would be either Galen Miller at Bikeworx or Tim Barker at Barker pipes. Both know what they are doing and both have campaigned the xtz engines very successfully.