i have gotten most of the done at this shop.
https://f80.bimmerpost.com/forums/sh....php?t=1702860
The owner Luc (i think) is and has been around for a while who does these work. There is also another guy, Raja but i never met him. They have done my mid pipe and ECU work.
You can call them.
Also, in Maryland I think there is another Shop called APAC. They did my calipers years ago and were reasonable too.
Besides that, i really can't think of any other shops that pop up for this kind of work.