One thing that just makes a GP4 file sound better is different guitar sounds and panning. I noticed you did panning on most but this is just a note to anyone. Have one guitar "distortion" and the other "overdrive" and pan left and hard. Doesn't always have to be hard, 100% because sometimes, bringing them in a bit sounds better and actually increases volume.
Gigaton
I hope you don't mind but I fiddled around with your solo too and made it fit the chords a bit better and put it in C#min.
Solo
Just a quick rundown of what I did:
Bar 2: Changed most of the notes but kept the same form.
Bar 3-6: Moved up 2 frets like I said so it's now in C# pentatonic minor.
Bar 7: Changed a few notes, D to D#.
Bar 8: Changed the 2nd arpeggio to a B major so it fit over the B major chord.
Bar 9: Made the bend up to D# instead of E.
Bar 10: Basically just arpeggiating a G#maj chord, which is the chord that the rhythm gutiars are playing.
Hopefully you can see by that now how I used the notes from the scale and tryed to make it fit over the chords that are playing.
The other stuff kinda reminded me a little bit of Lamb of God with the Drop D chromatic riffs etc. Bit of hardcore influence too.
EDIT: Did you look at the We're Not Gonna Fall solos that I tabbed??