Usually once a kick starts sounding hollow, it means you've scooped away to much of the low mid region. I generally find the mud people are talking about when saying "scoop 250Hz" is the result of the 2nd and 3rd harmonics of the drums Fundamental Frequency. for example, a lot of the slate kicks fundamental is at around 60Hz, so you'll find a lot of mud at 120, 240 and 480. Have a sweep around with a tight EQ, should become pretty easy to find.
After you've cleaned up the kick, heavily compress it. This is what people generally mean when they say Limit (as once you're over a 10:1 ratio you're technically limiting), slow attack, fast release. The add any coloring EQ / saturation / subharmonic enhancement to make it pretty.
I absolutely love the Waves SSL channel on drums. It's so tried and tested, but makes me happy in some many ways!
