PM hotrod182. He's (relatively) close to you and has been using nitrous on BMW's for a while and could provide you with good insights into the type of kit/jets and tuning.
Nitrous is very safe and reliable if set up properly.
Daily: 2013 e92 M3 MW FR DCT ZCP / ESS VT2 650 S/C, Akrapovic Evolution, ST BBK w/ drilled rotors
Track/Airstrip: 2011 997.2 Turbo S PDK / GIAC tune (9 second file), Champion Intercoolers, BBi exhaust / Ohlins coils+LCAs+endlinks
Beater: 2013 X5 3.5sport