Billy

I ran 2 fi bl 18's 3 or 4 years ago off 2 sundown 1500s in like 15 cubes net. Now I am looking at running them again in a scion xb. I have a box already that is 12 cubes net @ 32hz, how well would the bl 18's do in this box off sundown 3500d? Would it be too small, the site says 5-8 cubes each. thanks for any help