Is it documented anywhere by Toyota whether you get any improved performance with their dual exhaust option? I have it on the truck I purchased and was just wondering. It is a little over a $1,000 option, you would think they would have some facts!

Anything with duals should get better performance than single. If you had a good air filter like an Amsoil filter you should do even better. Pipes help you breath out but it doesn't do much good if you don't have the lungs to breath in you know? hope this helps.