The easiest way to raise the output levels of a track:
1) Add a clipper (like GClip or KClip) and
gently clip th
e higher peaks. If done right, you won't hear any difference and removing those peaks will allow you to raise overall levels without distortion.
2) Use one or more limiters to raise the levels. Never raise it by more than 3-4db per limiter instance.
3) Add VUMT to the Master. Set PPM to -10 (-8 if you really want to go loud). This should always be the last plugin in your chain. Repeat step 2 until the needles in VUMT consistently touch "0" during the loudest parts of the song.
All of this assumes you have already done any EQ and final compression/saturation adjustments to the track.
Regards,
Dan