Since you've named this rack "merzbow 101", there isn't really anything specific this rack is missing - this would be a pretty sweet noise box.
However, I would definitely find some way to fit a bunch of envelopes in here if possible. Preferably loopable and flexible ones with a decent range, for example. Go to the module finder and look up the top popular modules under both the "envelope generator" and "quad" categories. Or get a classic Dual Univeral Slope Generator (DUSG) style module like Maths or the Befaco Rampage (or the original designs by Serge still available from Random Source, although that'll get pricey). One of those would allow you to get more percussion and general articulation into this setup without making it too needlessly different (the Wogglebug audio section, for example, makes great percussion material). You could even use it to make your rack work more as a synth as well and experiment with noisy, raw takes on more melodic or rhythmic stuff. Not that you can't get here with creative patching using your current setup, but envelopes will make that a lot more satisfying. Plus it will make it easier to play this with a Keystep or something like that if you wanted to do so (which I recommend whether you want to make pure noise or play melodies or anything in-between).