Ok I'm only skill 50, and have 2 base perks and already bad guys I shoot with my bow don't see me when they are right in front of me. I'm shooting arrows in their nuts at point blank and they are still wondering where I am. It shouldn't ever be that easy. It seems like low level sneak is better than invisibility spell/potion.

Anyhow, any suggestions for a good sneak overhaul to make it a little harder would be great.

I've personally been thinking about http://skyrim.nexusmods.com/mods/16449 . It sounds what you might be looking for.