yea, that SX is trying to be ported. Building a big box allows you to tune lower and decrease port noise while increasing output. But there's limits to the output gain you get by increasing the size of the box.
I haven't spent any time working with that driver's specs, I'd give them a call. Also, you could take a look at a box program like WinISD or box planner and see what it comes up with. This will be usefull info to have when you talk with RE.
I'm doing two SX15s for my truck. 7^3ft and ports tuned to 28hz. They recommend 3.5-4.0^3ft per subs.
Heres the start of it. Ports are already in and rounded off to decrease port noise. Just have to cut the face plate to reveal them. Going to be another box around this covered and housing the amps. Should be nice when its done
nope you don't want to build the biggest enclsoure possible, for one it'll choke off the airspace into the cabin if you're firing towards the rear and not allow the bass to travel inside your cabin. And also if the enclosure is to big then the sub will just react like its playing free-air, while also lower lower trhe power handling of the subwoofer
also not sure if you mentioned the driver size but we'll need that info to help you.
i have like a 4sumthin cuft box tuned to 26.5hz wit 1 jl w3v2 an it sounds great it hits high an does the lows great an i think it sounds go0o0o0o0od it beated 2 15 kicker compvrs seald an 2 15 volfenhag seald an 2 alpine type rs 12s seald an i might b getti nit meter sunday hopefully