chan:The vanilla texture as a very "normalized" sun texture, the sun "aura" is almost at the same intensity as the "sun-disc" which will make sun easily blow out the sky and the Sun Corona makes that even worse.
I made a sun textures which don't blow out the sky as much as the vanilla sun does and it also don't have any noise at all, and above all it does not remove the long sun rays as most of the sun textures tend to do because they don't know how the sun rays are rendered!
You can try it out by downloading it here;
http://www.mediafire.com/?v8jc6l894na31fcIt has a very slight bleached yellow color to it, it's not something you will notice and ther is always sun deasturation if you do

I rtought it looked better than having completly white sun and sun rays.
Also to remove the sun effect on clouds change these values;
CloudsEdgeClamp=0.1 -- increase this to remove the sun affecting clouds effect.
CloudsEdgeIntensity=8.0
It doesn't remove it but it dampens it at least.