usually 8's do great in .75 cu ft ported box,so I'd make a box 1.5 cu ft with one 4 inch aeroport.This is similar to what I'm building for my xf.I have a roadster so my box won't be quite that big.I've built one box for the xf for 2 8's with a Kicker 600 watt amp and it hits hard and clean.This way the box is optimum for performance without taking up too much space.