The N54 motor is the designation BMW has given to its line of factory built twin turbo motors. It can be found in the E90 and E60 series cars (and a few others) that end in "35". ie 335 and 535. Those are what you want to read about and should help you along with your project. Also Garrett Turbo has a "turbo 101" on their website, TONS of information you'll find useful.