Hello,
Sorry I have not chimed in sooner, out flying this week.
Concerning our kits, the basic NOS/Propane kit is a single stage activation from a WOT switch and requires no maintenance or input from the driver other than throttle position with the right foot. The propane is an excellent fuel supplement for high concentrations of nitrous injection without the detrimental effects of detonation (the killer of any engine)
Our two stage systems do involve a second activation source that can be accomplished a few different ways and I recommend two stages for traction challenged cars or poor track conditions.
We have over 400 of these kits in use in Vipers with absolutely NO ill effects. The NOS/BTR Brand kit may cost a bit more initial purchase but is more complete and makes a very clean installation. The most important difference is that our kit does not use any of the engine fuel delivery system for nitrous supplementation. The engine fuel system on the viper is only capable of approx 580 hp before the effects of leaning and detonation become evident. Once this 580 hp milestone has been reached a supplemental fuel system will be required with the NX kit...this being some or all of the following; a fuel cell, higher capacity fuel pump and lines, etc. NX makes a fine product but one must consider what needs to be accomplished with these kits in order to achieve maximum potential of the product and add that to the price. Also, NX parts are not as easy to find while NOS parts such as jets and injectors are available at most any performance shop in the US.
Everything is about choice and I am happy with the choice of systems that I sell and use on my own Vipers. I have the greatest respect for both of these brands and regardless of which one you choose, your performance increase will be the undisputed best gain for the dollar..period!
Best of luck in your search,
Tom
P.S. Love ya Larry..........