Subwoofer advise

[escottl92]

Good day all, my question is which would be better suited for my needs 2 15” or  2 18” subs??

i have bigger alt, doing big 3, changing battery underhood, adding secondary batteries. 

I have 08 4 door F150, pulling back seat out, no wall! This will be daily driver/completion truck as well. 

I will be running an ampere AA5000.1D amp

any input would be appreciated 

[Joshdashef]

Are you doing a blow through or a box in the back seats ? 

I feel like you’d be hard pressed to fit two 18s in the rear seat area ported maybe sealed. 

[escottl92]

No blow through

i have 39 sq/ft to play with 

I’m hoping for ported