I found it very tricky to find information about this kind of film. It may be discouraging at times but here are some tips.
From my experience and many many hours of reading reviews online, I can say I found a way of developing a B/W ultra-fast film properly.
Fast films range between 800 to 3200 ISO. As anyone can produce an 800 ISO, a 3200 ISO film is only made by a few companies like, Ilford with its Delta Pro 3200, and Kodak with its T-max 3200. In fact, this type of film is 1600 ISO made to support 3200 ISO or higher.
This type of film demands a lot of knowledge about exposure and the kind of developer used. I found best to use Kodak Xtol as a developer. However, other developers are bringing different results which one may like.
From my experience with this type of film, it is best to expose at a slower speed and push one stop. Ex: expose as a 1600 ISO film and develop as a 3200 ISO film.
Also, developing times are available on the manufacturer’s website, and for a vast variety of developers, just use a Massive DevChart, which brings information about developing for films, times and developers, fixers and other information.