I've been studying the possibilities and the theory for the past year. Essentially, after the primaries and collector, one 2.5" pipe does just as well as 2 - 2" pipes. There is really no performance improvement to split them. There is, however, significant weight gain.
Getting headers like Trueleo's is a much better move from what I've read. Now if you do up some custom headers, you can route true duals, but for all the work, it really won't benefit your hp and torque.