I replaced the SPF ceramic coated pipes with stainless pipes from Stainless Steel Specialties. Good seat-of-the-pants performance increase, much better appearance and, yes, an increase in volume.
Have a slight golden hue at the header/collector but the rest of the pipes take no work at all.
I went with a pretty large (long) heat shield to help protect the legs of the not so aware passengers and lookie-lous.
