I've tried a couple different setups with my H3's. Those that Bill has for sale would be killer. I have ONE R-10D sub and it does the job nicely with the H3's. I've also had a couple DIY horn subs the THTLP and the Anarchy 25hz tapped horn. Both of these worked very well. If you can find the drivers I would build a couple Anarchy subs they really are great with the H3 and any series Heresy for that matter.
Great choice by the way, I love my H3's.