If you did want two pipes to the back i would have to say do the x pipe also. It would bring back the scavenging affect that you want. It will change the sound some but not much. If you don't want to spend the money on it you can make your own by getting two 45 degree pipes, cutting the outside of the bend flat on both and weld them together. Very simple to do, I did it on my 4.6L with 2.5" off the manifolds and you wouldn't believe the power it freed up. Not to mention it sounds mean as hell!!!