Sorry, I'm biased in that I'm not a fan of nitrous.
I agree it can work, and work well, especially when you do your homework, but I don't have to stop at a shop for a refill of boost
Kidding aside... it's hard on a motor, lots more stressful than turbocharging IMO. Progressive controllers have helped a lot.
I've thought it through and done reading on it, and I'd rather stick with straight boost. If I was dead set on doing it in a *stock* Syty... here's what I'd do:
20g with 14cm2 housing (big exhaust flow)
HKS or serious wastegate on crossover
TPI plate setup
look into a propane setup like is used on Vipers (versus wet shot, where I don't trust the intake to distribute a fuel evenly)
serious ignition system, look into non-projected plugs
low low timing fueling ~10 degrees to start
50# injectors, overfueling at first, start pulling fuel back as you tune
You *could* scale the MAT versus fueling table strongly for a dry setup, but it'd take some real tuning to discover the MAT values the nitrous brings the temps to. I've even gone through the code to do it this way (you didn't believe me when I said I looked into this eh?)
Use the EGR output as a progressive controller, then there is a direct fueling factor that is versus EGR %, and you could dump in the fuel to compensate for the EGR (nitrous). Detect knock? Close up your EGR (nitrous) solenoid. I was going to look into the electronics of this, but gave up. This way would be very safe, as it is a pretty good closed loop system... throw nitrous in, if it knocks, shut nitrous off. Enter the wideband 02 for some extra tuning nonsense... and away you go.
There is a LOT of potential for someone into tuning and writing their own code... you can have some real fun. I already have a list of things I want to do with my truck..

Well, actually drive it is first on the list 8)
Anyways, after talking options and whatnot, I decided I'd rather work on straight pressurized airflow, rather than buying a lot of parts, refilling bottles, worrying about extra fittings, bottle pressure etc.
Heck I know of this one truck that has no porting done, using iron GM heads, a mild cam, and stronger internals, made 550rwhp on lots o boost.
If you wanted to build a reliable nitrous build, you'd need at least those parts IMO, and that power level is fine with me. I'd rather tune higher boost than high boost & nitrous.
Anyways, I can discuss options like this til the cows give ice cream.. but everything tells me not to use nitrous. I still like to compare the NMCA classes which were running mongo Nitrous motors versus small (relatively) turbocharged motors. The turbo guys were kicking ass and taking names, on motors that lasted 10 x better than the monster nitrous motors.