. Good decision. Always use a carb switch, I use 2 because I spend a lot of money and don't want to lose a round because a micro switch pukes out. I also use 2 relays, same reason. A purge is a good idea, especially guys with bottle in trunk. My bottles are in the front seat, and I still use a purge, if you're not trying to run a number, than either way is fine. For a single stage set up, a basic Y-block feeding the 2 regulators is very easy to plumb and much cheaper than a log. Don't forget, the later you activate, the less help N2O is. The most gain is at the hit, if the car can handle it. Also be careful unloading the car if you hit the N2O down track, especially around the shift. Have fun, race safe!!! .