whats better for my setup??

hey guys i need some help...
what i have is 2 dd 9515 in a pwk box thats tune really low for music..
and to power the subs is a new ddm3a. nothing is hook up yet just trying to get all the parts together..
My question is it ok to get 2 kinetik (3800 or 2400) batteries and a isolator and not get a aftermarket alternator????
my goal is to get a volt meter that reads in the 14.5v then when i crank up the bass i wuold like to drop to 13.5v.. what can i do??

also i was thinking about getting the xs power 14v battery in the front and back, but ill my electrical system for the truck handle 14v?? i have a 04 gmc truck.
again im doing street beat and demos so i listen to everything

14v cell puts you in street beat 5

Yes you could add 2 extra batteries. I'd look into maybe a MLA module or xs vcm. But Ive known people to run alot more power on a similar setup.

Ok I understand there's a few paths to choose from but what's the fastest and easiest
Way to go about this.. To recharge I have a 260 amp alt.
What's the cheapest also???