Well one thing I can think of is it will be louder in the back seat but it may sound better in the truck because the sound has less of a space to bounce.

 

fatmat is just as good as dynamat and a fraction of the price...well i lkie. not just as good. but for somebody who's not doing car shows its plenty good enough

 

I don't think it'll sound good or be louder and it'll virtually eliminate the back seat useage as well. And any port noise on the box or boxes will be far more noticeable than if they were in the trunk. All I see is bad things from this. Just do a single 10" setup if you just want a little bass and very little space taken up. Sundown Audio makes a savage 8" sub too, that thing surprises everyone who listens to it, it sounds and plays alot larger than it's cone size would suggest.