there should be plenty of room for 4-15's if u arent concerned with losing cargo space
im planning a similar install in my magnum, i just bought my sub amp this weekend off one of the guys in the forum and then all i have left is components, this is the list of goodies i have so far
4-MTX 8000 10" (8104) from a few years back, but they are BNIB
Kicker 600.4 for front/rear stage
Kicker 1200.1 (what i bought this weekend, should be here by this thursday
i am going to get a custom box built to house those 4-10's it will be tall and be level to the back seats, i have to maximize cargo space cuz i have my kid's stuff that will go in there and my amps will go underneath the cargo area
that car is going to be a ***** to do the big 3 on, the battery is in the back, BUT on the upside, the SXT line comes with a 160amp alternator stock