I did not modify the cross member for duals, I'm running a single 3-inch system. Today I got it finished up to the tailpipe. It hangs no lower than the factory system and I was even able to reuse the original hanger with a little modification.
As far as trimming the headers, I cut mine up to the flange. I didn't see the point of having the small sections between the ports. Eventually I will trim the gaskets too.
Sounds pretty good so far:
http://www.youtube.com/watch?v=RUW2WMk7EBs&feature=youtu.be