What drivers are you using for your IB? I have a 4 Tempest IB driven with a 2400 watt QSC amp. I find that the amp is hardly doing anything at all but the SPL is shaking the house like crazy.
I hope Mike does not see that I spelled his name incorrectly. Looking at the link to his site I see that he does not seem to show a sub at the rear any longer. I emailed him about the sub and how he got the info to it. He told me he ran the rear surrounds to it first as was stated above as well. Nice guy that Mike.