the speakers can't handle the bass from the subs, that's all....
But, WOW HUGE diff!!!!! The bass hits a LOT cleaner now. You feel like all the noise is right in your face.
However it didn't do a damn thing about the tinny rattle I still have. The Dynamat cleaned up like 90% of the rattle, the little thin strip where the key goes in the trunk rattles a little.
But yeah, I am very pleased with the results! It took me A little over 4 big cans of undercoat (make sure you buy the ones with sound dampener). And reason why it took me so many is that I didn't half ass it, I sprayed the metal, then the plastic covering (No worries, none of it is actually visible.
And yes the new pioneer's sound MUCH better than the Alpines
Next Sound mod = Pioneer PREMIER Hu with XM Radio