Ficz,
I think there are many mods from different shops.
1) Bodykit
2) Engine
3) Suspension
4) Aerodynamics
5) Interior
6) Exhaust
7) Tinting
8) ICE
9) Original BMW Performance Mods
And list goes on. Each of the item above can be found from different shops. It's ain't local made where you can go 1 stop shop like brothers to get stuff for the car.
Therefore, I would suggest that you do some research on the mods done by people locally and overseas. It would be good for you to find some BMW Magazines and read up on the BMW mods.
Cheers, Welcome to ownership of BMW