I know of a couple folks that installed them at another titan site.
If I remember correctly the results were far from spectacular. They will make your Titan run a lot richer so you will definitely want a tune job after install.
Folks are having pretty good luck with the Powerflow headers from what I've read.
I'd love to install them but to much of a PITA for me to mess with. I'd rather spend the time installing them on an old muscle car.
Maybe someone else can chime in with more "experienced" info.