System finally installed...now another question

Thanks for the help getting everything installed a couple weeks ago. Now the setup is complete, but I have a question. Not really suprising considering this is my first real involved sub install.

Anyway I have a c300.2 powering 2 mm2104dvc's. It sounds great for sustained notes, but when I turn the volume up the hard bass drum hits are not as hard or as tight as I would like. They are not very tight at all. So any ideas what might be the problem.

More info on the system that may be pertinant:

I have an 8 gauge wiring kit powering the amp (could this be the problem, I know the specs say 8 is enough, but does the amp need more power?)

The subs are mounted in my spare tire well. I measured carefully to make sure it was the right size. The bottom and sides of the box are fiberglass...lots and lots of fiberglass to pratically eliminate flexing, and the top is MDF. Could the problem be with the seal between the MDF and the fiberglass? I used liquid nails to seal it, but should I go back and glass the seam?

Thanks in advance for any help.

My first guess would be in the tuning.

Try different crossover settings, level settings and so on.

Thanks Mac, you were right. I feel so dumb, I thought I had tried everything...I forgot to check the input selector switch. I can't believe I missed something that simple.

Anyway, it sounds great now, I'll get pics up later :)

I always glass the seams just to make sure