demon 3" exhaust routing?

I have my X pipe hooked to my headers. 3" pipes. They seem to fit fine in the two indents in the transmission crossmember. I am now trying to figure out where I need to locate and what size and shape mufflers? Do the mufflers just go up against the floor of the passenger area or further back? I was thinking about a 4" thick muffler. I am thinking I want something with no drone and I understand there are a few which do well, but don't know which ones? Chip Foose always talks about the magnaflow? Should I put a pipe off the xpipe to move the mufflers further back? Any pictures of how your setup is. I have Dougs headers with the dougs 3" x pipe on my 340 motor. Where do I go from here?