I notice that there are very little/almost turbocharged bmws around the GTA. Why? No idea! I must admit for a first timer planning/building a setup may be difficult due to making the setup perform the way desired, getting the right parts, taking into consideration EVERYTHING needed to make it all work...etc etc. In an attempt to maybe encourage the next guy who may be interested in some boosts in their life I'll include a few things to read up on from Garrett to getting an overall understanding of a turbo system.
Turbo Tech 101 (basic)
-Journal bearing vs Ball-bearing
Turbo Tech (advanced)
-Turbine housing A/R sizing
-Exhaust manifold styles
-Compression ratio with boost
-Air/Fuel ratio (AFR) tuning: "rich" ratio vs "lean"
Turbo Tech (Expert)
-Mass flow rate
-Turbo speed lines
-Plotting points on compressor maps
Once you get through those you SHOULD have a pretty good handle on a turbo system. There are still a ton of other things realated to a turbo setup like boost control, chemical intercooling and such. You can go read up on those yourself to understand more
If you have any other turbo related question to turbocharging our BMWs ask in this thread and i'll try to answer as much as I can.
Good luck and happy boosting!