It is a matter of looking for the techs that relate to whatever component you are changing. In this case the hyperdrives and so in game you have techs that give you a new type of hyperdrive, and techs that offer an increase to that hyperdrive type. So taking the top end as an example you have I believe three tech stages as follows.
1.The tech that unlocks the Torrent drive (the name escapes me)
2.Hyperspace path slicing, this offers an increase to the Torrent drive stats
3.Unified hyperspace theory, this offer an additional increase in stats.
Now the Torrent drive itself has it's base stats determined in the components.txt, however if you look at the two tech listed above in research.txt you will see something like this.
PROJECT ;171, Unified HyperDrive Theory, 7, 16, 1, 10, 0, 0.0,
COMPONENT IMPROVEMENTS ;51, 7, XXXXXXXX, 105, 4, 0, 0, 0, 0,
PARENTS ;170, N
This shows how the tech will effect a given component in this case a hyperdrive, each number corresponds to various things such as the component type etc etc, all these numbers are explained at the top of the research.txt. In this case though XXXXXX represents what the new hyperspace speed will be after this tech. So if say change the torrent drive to move at 500 but forgot about this tech then you would suddenly find your torrent drive ships moving at 32000 upon research of this tech (I believe this is the default value).
This applies to each and every tech that has an effect on a hyperdrive and also includes changes to things like jump delay/energy use etc. So if you make a change to any component types you need to remember to make changes to the techs that will effect them later also. It is a bit of a headache due to the way the modding is laid out, you are basically defining 3 versions of the same component for each and every hyperdrive. Space empires 4 was like this and it's data files were a nightmare and tedious at best to edit, Space empires 5 went the route of having a single component entry and then having a line that told the game how each tech advance increased the component in percentage increments etc, it was a much better method and far quicker to edit without going into triplicate and more each time. Really do not understand why DW has used this method.
One final point is that even though these are all .txt files use something like notepad++ to do your working as it clears up any mess and makes the entire thing almost tolerable to look at for more than five minutes.