04 silverado stereo doesn't sound right

I installed my system this weekend in my 04 extra cab silverado and it sounds o.k. but it just doesnt sound right. Here is a list of what I installed:

*Pioneer Premier 860mp*2 Image Dynamics IDQ12 v2 d4's each in a .85cu ft enclosure  (.85 is with the displacement for the woofer taken out). Box is downfiring under the rear seat.*A/D/S 346CS component set  6.5"* Directed 1200d amp for sub 600x1 @ 1ohm. Running it at 4ohm's so 300x1* Directed A802 amp for comps.  Running at 4ohm's so 2x150.

My problem is these subs dont sound as clean as I thought they would. They play rap music very clean and hit hard, but for rock and punk music they sound muffled or distorted. What could it be?

Before I had everything for the silverado, I played one of them in my S10 in a bigger enclosure with the same amount of power from a older fosgate amp and they sounded cleaner but didnt hit as hard. What can I do to make these things sound better? Please Help!!!!

how is your decks eq setup, and what are the crossover setings,how much space from the sub and the bottom of the cab

The sub is at 80hz and the space from the front of the sub and the floor is 1 1/2 inches.  What other setting do you need?

Not a dumb question, yes they hooked up correctly!