Its also rather a chunky neck compared to any other T-Bird I've played which is a little disapointing as I have the impression that the real thing has a very slim neck.
That is one thing that puzzled me too about your bass. It is the only BaCHbird I've seen that had the volute and the chunkier neck.
With every batch of BaCHbirds BaCH seems to feel the need to change something; The second batch didn't have the belly cut. But the body was substantially thinner than the body of the first batch. There was a series that had a different angle between body and neck (which resulted in a lower set bridge). Your bass obviously had the volute plus chunkier neck.
And a month ago I sent a BaCHbird to Japan that had an arm contour...
As for changes made to my own BaCHbird.
I made a new pickguard.
I added a Gibson Bicentennial pickup at the bridge. I placed a chrome cover over the Artec pickup.
I replaced the pots. The volume pot for the Artec is a push pull pot, allowing me to switch to single coil when desired.
And of course there's still the BaCHbird Deluxe. A one off pilot. A Transparant Red BaCHbird with Chi-Sonics, new wiring with CTS pots and switchcaft jackinput. New pickguard. And Res-O-Lite machine heads.