Nice flex, when i had my 2 15s, i threw them into my jeep on a rockford 200-2 wired to 4 ohms in a sealed prefab box it flex/ rattled it to hell 4dr jeep cherokee. Cherokees get decently loud on nothing
Try removing all the trim panels around the trunk opening, and the spare tire cover, thats how we fit my buddies box in his car, and just slide the cover under the box and set the trim covers back on.
If it was me, i would take the kit off, lower it, have a nice set of black 16" rims, swap a b18c1 in it, and put like a single 12 in a t-line in the back, with 170 amp alt and a upgraded front battery and black out the windows, then call it done