Not by any means an expert on systhesis, and I mostly just popped in to say this is one of my favorite song ever, but here's a thought.

It kinda sounds like the synth thats being run underneath it but higher, and with perhaps a saw LFO applied slightly to the gain running real quick to get that jitter. A very short delay is used to thicken it up a bit. I'm unsure on what kind of osc is being used but juding by the detuning I'd say a Multi Oscillator (I use reason, so that would be found in Thor not really shure about what other programs would use/what it would be in them). There is some pretty strong harmonics in it, and perhaps some bitcrushing? I'd also hazard that it could be a sped up version of the lower synth that comes in irght after its couple of bars.

:D