Yeah I've been told a single 10" IB is not going to cut the mustard. So I've had the 10" in a ported enclosure in the trunk and it was stupid loud, however I hate anything ported in the trunk of my GN. Boomy as hell and does not hit hard. That same sub in the same box in the back up my hatch hits stupid hard, whether it is in my WRX, my old CRX, hell even in the back seat of my trunk.
I have two 1st RF Audiophile 10" subs facing the rear in the trunk now. They used to be ported in there and it was horrible. Went reverse phase and it was better, but not hard hitting. I redid the box sealed and they were sounding better, but not right. Just the other day I tried switching them back to in phase. Low and behold they are much improved. I think I will stop screwing with this car and save my IB aspirations for my '59 LeSabre project.