New to 8 strings and I can't get them to cut :(

I am having the same issue I think. Its like if you add mids in, it gets messy so quick, but when you take them out the guitars end up missing. Maybe play with the mids a little, seems to be the problem area.
 
I think the high mids on the rhythm could be boosted maybe, it just seems a little dark and behind the mix a little. what's your eq like? also, the main riff thats going the whole time is kinda harsh i'd bring the low pass down some and take the bite out of it.