Rich, there are so many ways they are wrong mate.

They dont control the flow of it properly, they hit it in stages instead of progressively.

They dont pay any attention at all to flow dynamics along the pipe, changing pipe sizes all over the shop, the solenoids they run arent matched to open and shut at the same rates for the fuel and nitrous which leads to lean conditions, the piston designs they use are wrong (cant really disclose details of that in an open forum) they locate the solenoids too far away from the injectors meaning that they exagerate lean conditions as nitrous travels quicker than fuel.

And thats really just scratching the surface with stuff i can talk about publicly, i could go on and on about it mate there are SO many things they do wrong, but my friend wouldnt be too happy if i went into much detail so im not going to, as there is massive money involved in racing at that level so sometimes a little secrecy is useful.

Some are better than others of course, but most of them share all those problems.

Several of his competitors, even some of the guys beating him still due to the amount of extra money in the rest of their cars (he has a 50K a year budget and some of them have 10 times or more that money) are currently trying to convert to the same system but wizards of nos wont currently supply them as they have signed an exclusive deal with Johnny that hasnt yet expired, so for now its only him running it.
As soon as one of the front runners swaps over though everyone will obviously notice the difference and will follow suit, hence what i was saying that you can expect in a few years to see them all running completely different systems to they do now.