Do you use the unmodified attribute (before racial modifiers) when determing the cost of increasing an attribute for a non-human?

For example, if you want to increase a troll's strength from 9 to 10 (+4 racial mod), does it cost 20 karma (10x2) or 12 (6x2).

Add the racial modifier. It is natural.

By canon rules, you add in the racial modifier before calculating costs, as toturi has mentioned. As a house rule, I omit the racial modifiers when determining attribute improvement karma costs. It makes more sense to me to do so.