If you want some seriously heavy sounds try playing harmonic minor, diminished, harmonic major, hungarian major or bhairava scales etc. You could search for "Andrew Francis" to find my postings with these scales or you could use the GAFF fretboard mapper.

http://www.power-chord.com/gaff/mapper/

Tons of gain, screaming pinch harmonics, scooped mids. Palm muting wide tremolo arm vibratos. Sounding mega-heavy is great fun!