a few things i can add. along with bringing up the guitars, you should mess around with reverb on the vocals. not much, it just seems that the entire band has some room to it and the vocals sound really isolated.
with the gain, its all your preference, imo i see that it could be brought up a tad, as i said before this would totally require you to redo the guitars. when you bring the gain up a little bit more than what you have, the fundamentals of the notes are going to sustain more, and then the guitar will become a little bit smother on the ending and during the sustain. if you add more gain and you loose the sharpness of your attack its too much, you just need enough to smooth out the post attack areas. during the palm muting parts the guitar will still sustain in a desired way as i have heard from the way you are playing it. it will make the overall sound heavier and meatier and help relieve the nasally sound that happens sometimes. just use that as a future reference when your doing a new song, check it out and see if it works for you...or not, trying new things never hurts, you can learn a lot from stepping out of your normal comfort zone. Hell i found out that i prefer the AC120 cab impulse for my guitars, a vintage cab, and it makes my signature guitar tone. And prior to, i avoided vintage gear becuase i thought that there was no reason for me to use any of it.
