Neat song! I like the drums and the pace. What I think can be improved: The mix is a bit empty, particularly in parts without synths. I feel like the guitars could be louder. The song is somewhat repetitive; I think you're right that vocals would have given it more life, though you could also add lead guitar or other instruments instead. The short synth notes in the blast beat parts feel a bit out of place, perhaps reverb could make them sound better, or make the notes themselves longer. All in all, I like it, keep it up!