Yes. They are refered to as infinite baffle. I have an 8" in the rear deck of my SVT Contour. They add low end, and help fill in the missing lows from the 6½'s up front. I know they make 10" IB subs... but I'm not sure of it's use in that opening behid the seat. What I think I may do is build a box in that space, although I have not even pulled that cover off to see how plausible such an idea may be. There was mention of using Infinity's Basslink in that space just a couple days ago on these boards. Try a search for that.
A forum community dedicated to Nissan 350Z / 370Z and Infiniti G35 / G37 owners and enthusiasts. Come join the discussion about performance, modifications, troubleshooting, exhaust, turbos, maintenance, and more!