Okay, here's the words for Increase [Attribute]:
The Force of the spell must equal or exceed the (augmented) value of the attribute being affected. The attribute is increased by an amount equal to the hits scored.
Since you have to declare the Force before you case the spell (SR4A, pg. 183, Step 2), you don't know what the stat will be after rolling, therefore you have to use the stat pre-rolling.
So if Johnny has Cha 3 and you cast Increase Charisma on him. you must cast at Force 3+.
Casting Improved Intuition on Sarah, who has Int 3 (5), you have to cast at Force 5+, since the Force must meet or exceed the augmented rating.There is no threshold that has to be met; therefore, each hit (up to the maximum of Force, SR4A, pg 182) is added to the existing Attribute Rating. Additionally, no exemption to the rule of maximum augmented ratings is specified, so if you hit the augmented max before you hit the Force of the spell, additional hits are wasted.
Casting the spell on Johnny at Force 3, you get 5 hits. Discarding 2, that leaves 3 hits, increasing Johnny's Charisma to 6.
For Sarah, the Improved Intuition spell garners a total of 4 hits which would be enough to bring her augmented Intuition up to 9. However, as a troll, her maximum augmented Intuition is 7, so two hits are tossed aside.@Kot: How does Increase Initiative break the rules? To keep four hits, you have to cast at Force 4. Force limits maximum
hits, not maximum net hits.