Feeler:
 

I am currently in the process of building a custom fiberglass box for a wrx sedan. It is being molded in a 03 wrx. I believe, when finished, this should fit in all 02-07 wrx sedans. I built one prior to this and loved it, but went to something smaller. I am building this one to sell again. If anyone is interested in a custom box please let me know soon so you can have this one. The reason I say this is for when I cut the hole, it will be specific to the size of the sub you will be using. It is now open to be cut for an 8 or 10" sub only. I could possibly due a 12, but not sure air space would be correct.

I would like to get around $150 for the box. It will sit in the back left hand side of the box and be secured in place by the arms on the trunk.