Well, J-16D program itself likely has different interior layout to deal with increased cooling and power generation demand + having just additional systems that needed to be fit in there to carry out all the EW effort that it would need to do. A normal Y-9 based EW aircraft doesn't have much concerns about system & computing sizes, since its so large.Keep in mind that electrical generator power is tied to the engines and only take up a tiny fraction of the total power generated by the gas turbines, and the engines can always just be upgraded if total engine power really isn’t sufficient.
But to fit that in the interior of J-16D and keeping the antennas far enough to not have interference is a challenge. It probably took quite a bit of miniaturization effort to get all of that fit into this platform.
So, as we move forward, if you want to have say 5x power running through internally in the same interior space, there is actually quite a lot of work involved.
I can tell you having been working on a project recently that required putting electronic board inside of something, the number 1 concern we had was heat dissipation. And then after that is how big the battery size needs to be.