I've got an '06 GT with the stock speakers.
I've had this head unit for quite a while: Sony CDX-GT520
All I'm looking for is a performance boost that wouldn't require a separate sub or amp (unless I really need the amp). One of the reasons I got this car was because of the utility of the hatch and cargo space. So I don't want to waste it by putting in a huge sub.
Not looking to spend a ton of money on anything too fancy, but some extra punch in the bass would be nice. Any suggestions?