After a lot of research and head scratching I've decided to take the plunge and go DIY, I currently have a Monolith + behind an at screen in a dedicated room measuring 17' x 9'. The plan is to keep the sub behind the screen but to make more room so I'm not limited by space for the cabinet. I built a solid plasterboard wall when I first made the room with a small opening inside which I housed my equipment but I soon tired of this and hid it all behind the wall, this now leaves me with a large space for the new sub. I like the look of the Dayton Audio UM18-22 18" for the driver but I'm not yet decided on sealed or ported cabinet, the space I will have to play with is 105cm W x 50 D x 150 H. I have had a quick play with WinISD and it seems it should be able to accommodate either design. I know there is a lot of knowledgeable people on these forums and hopefully with your help I'll get a decent end result (fingers crossed). As It's my first build I think I'll contact gordy on ebay for the cabinet cuts as it will be my first attempt and have I a limited tool selection!