I highly doubt anyone is still reading this thread, but I am, so perhaps someone else will after me.
It's probably a bug, but the Illusion perk "Aspect of Terror" makes fire spells do +10 points of damage. So for example, my character with Aspect of Terror and the first level of Augmented Flames (1/2) does 41 points of damage with his Firebolt spell and 20 (!) points of damage with the formerly weenie Flames spell. That's right, 20 points of damage per second from Flames.
I guess Fire spells have a Terror quality to them whether you have the Searing Flames perk or not, which is why Aspect of Terror affects them, but I'm sure this is a bug. A very fun bug though =) this is still current in version 1.5.