Anyone has a Twin Turbo or Supercharger system installed?

Does Anyone on the board that has Twin turbo or supercharger system installed on their car wants to share some info as far as cost of hardware, cost of install, twin turbo or SC manufacturer, Dyno HP specs and so on.
Or just mention that they have it , curiose of how many people there are with TT or SC systems.
Thainking about TT myself, on 1991 850i , was putting it off for a longest time because cost and time. But this summer should be able to start something would it be buying an aftermarket system or custom. Any input appreciated!