How to get a fat kick

Use two Vitalizers in series. On the first, bring the bass all the way to soft, mid-high tune to ~4, and the process to 15. On the second, bring the bass to tight, mid-high tune to 8kHz, and process to max.¹

Another technique is from Bob Powers, which entails parallel compressing with a dbx 160 and boost the parallel track with a Pultec with at either 60 or 100Hz.²