Yes, I have found that running obj's thru uv mapper allows Bryce to better map them. Some have told me it makes no difference if you are using Bryce textures, but experience has shown me otherwise. Whenever I have a problem getting textures to look right on something I run it through uv mapper and give it box mapping, then save it out and import it into Bryce, then parametric mapping works great with Bryce textures.