OK I currently have 1 CompVR 10 kicking in the extended cab portion of my truck. I am going on a budget but want to add a lil more sound. I was originally thinking 2 10's but a few people told me to go for 2 15's in a sealed box. I have no clue how big of a box I would need but I do have an extended cab Ranger with a fairly good space for a larger box. Any suggestions?