I'm useing JBL HTI8's http://www.jbl.com/home/products/product_detail.aspx?prod=HTI8&Language=ENG&Country=US&Region=USA&cat=HTI&ser=HTI for Surr/Surr Backs in my ceiling and was wondering if anybody would think that building boxes for them would improve the bass output.If so what size would be recommended,keep in mind I have to keep them in between 2 ceiling joist which are on 16 inch center so the box is limited to around 14-1/2 inches wide.Thanks.