my suggestion is to go from a 14 (stock) in the front to a 15 and see how that does. I run a 15 or 16 up front and leave the back 41 (stock) alone. Depends on what type or riding you do too.
Not sure that gear ratio and speed mater to you, but here is a website that you might find interesting. Gives speed ratings for sprocket sizes.
http://www.dfn.com/benkaren/speed.xls