Hi and in advance thank you to those of you that can help me. I shoot with a Xpan, using Velvia 100. When I have the film developed, I scan them with my Epson 4870 to a DPI of 4800. When I test print on 8 by 10 photo paper at 300 DPI, on my Epson 1280, the pictures are very crisp. The colors jump out at you.
The Problem for me is when I print at 300 DPI at a size of 12.94 by 36 on Epson Premium Luster Photo Paper, the intensity lowers. I don't get the same crisp hot colors. Is it the nature of the beast, asking too much from my equipment. I am looking fro vibrant colors. Any ideas?

How familiar are you with color management? If your scanner, monitor, and printer are not properly profiled, you'll always have color problems and you'll never get a consistent color match between monitor and prints, especially if you use a variety of papers.