To me it sounds like the main bass / growl synth could have some more high end to it.

also, about the composition itself, the melody/chord progression seems kind of repetitive, I think it'd be more interesting with more variation.

This might be just me, but there is some empty space in the mixdown that could be filled. Think as of what Skrillex did with the drop of Make A Move remix http://20before16.redbull.com/skrillex/, but it doesn't necessarily need to be sirens (or high frequencies at all)

Otherwise, solid sound design, old-schoolish vibe, I like it.