I have the 1 JL 10 back there now. It sounds good, but not enough bass for my taste. It'll be tight, but I can get 1 12 back there. Sad to say, but I'm leaning back to Kicker. I just know what to expect sound wise with them. I've always heard all these great things about JL, and the sub didn't quite meet my expectations. A lot of that is probably due to the inept sound machine also known as a Jeep Wrangler.