i like the toned down feel. you might want to consider taking out that metallic pulse thing a little earlier each time, and maybe thicken up the atmosphere a little more as the song progresses. hmm i'm just throwing shit out there, but maybe if you started doubling up that pulsing thing and addidng some sterio delay as it progressed it might add some tension. it's definately sounding good already tho.
hope that's usefull.