Korg MS2000
As far as we know this was only used on the Kicking Cars EP, as it came out after they'd finished working on D>E>A>T>H>M>E>T>A>L, and Owain most likely didn't get it til at least a few months later.
The synth was used for Kicking Cars (possibly), Sodium Chloride, and definitely CUT, where the built in arpeggiator and/or sequencer were used to add the main synth line in the song. I'm looking at grabbing one of these synthesizers at some point but am currently using a Korg Minilogue instead.