If you don't have to use a shallow sub, then don't. I have a 10" shallow behind my rear seat in the factory location. It suits my needs as I very rarely listen to loud music anymore. It's certainly light years ahead of the poor factory sub, but it could certainly be better. I didn't want to lose the space under my rear seats, so I went with the shallow behind the seat. If you don't mind losing that space, there are dual sealed 10" enclosures on Ebay specifically made for the RL. Ported enclosures really need to be made with a specific sub in mind. Each sub has different characteristics and if the enclosure doesn't fit those specs, it will not sound right. A sealed enclosure is way more forgiving.