This is something I've studied for years. I've managed to attain those levels and with some authority. I have produced masters slightly hotter than the latest Rush and Foo Fighters recordings, and still get compliments on how powerful my masters are. And I did this ALL with plug-ins!!
I'll give you a good hint: Perceived Loudness is not the same thing as Energy.
A better explanation is this: If you are unable to get the volume as loud as they can, there's obviously an important reason. To get something quite that loud requires compression and limiting. Mashing a mix into oblivion is easy. Keeping it dynamic, punchy and musical....now THAT's the mystery! If you can't get there with simple compression and limiting (in that order), you need to evaluate and research what frequencies or instruments are "killing" the compressor or limiter. Many times, I find low frequencies in guitar and kick drum as culprits. Sometimes, just a rhythm guitar or kick drum recorded with a large-diaphragm condenser will produce frequencies well below what you'd care about hearing in a final mix, Use some low-cut filters to help here.
The next thing I figured out is, what plug-ins I could use to get a little more out of the mix in terms of volume and punch. I found a few plug-ins that help more than others, then researched and discovered exact attack and release settings that will allow maximum punch without the pumping effect being noticed too much.
Mastering Engineers are good at these things for a reason. They know how to do it, how not to do it, and when to stop doing it. Plus, some places, such as Grundman Mastering have specially built equipment that can only be gotten by using their services.