When I said 'tight' I didn't mean the playing (although some humanisation wouldnt hurt), I meant the tones.. and on the drums. For faster metal genres you probably want a really tight drum sound so its really clear. But for slower things, making it too tight makes it sound really small, especially when you're playing so slow (relatively speaking, not 250bpm blast beats). Most pop or punk records nowadays have pretty fucking HUGE drum sounds, huge everything really.
And thick guitar tones will only cloud up a mix if you've also got huge roomy drums and a loud bass. But you don't have either. You've got thin guitars, bass that sits under everything and doesn't stick out, and small drums, and so if you want to make that work you need a really big guitar tone. You need to emphasise some things and let other thinsg suffer, unfortunately. Personally I'm terrible at mixing guitars, so I get a really nice drum tone, a loud, distorted, wicked bass, then I put the vocals in however they'll fit and then EQ the guitars so that they fit around everything else. Otherwise they're too bright, too middy, too whatever, I can never get them right.
If you're a guitarist (assuming you are), then you're probably gonna want a huge guitar tone, with a bass that just backs it up, and then whatever drum tone fits. I don't know A Day to Remember.
And what do you mean by "the muffled guitar is due to using the same amp emulation with slightly different settings."? You mean you used different settings each side? That's generally fine (although try to keep them fairly similar.. most people, myself included, just go exact same settings both sides), but its not going to lead to muffling. Muffled = not enough high end. boost the treble or pres.