I have heard of a few different tricks people do with their supplemental injectors like use super chilled or trick fuels to either cool the flow or improve the fuel energy of the mix or both.

Concidering that this guy is a champion and probally has a few radical trick mods to achieve that, it might be the reason why he only talks about the basics of his system, but does not mention anything about his "supplimental" systems. Its not exactly the kind of tip you want to pass along to possible competitors.

As he states he may not be spraying with NOS, but he may be doing something equivalent like spraying a little nitro-methanol into the mix with his secondary injectors.