Are you serious? You're increasing wear&tear on the engine, tranny, brakes, etc by means of performance tuning, and you want the dealer to pay you something for that?
You should be happy if they don't charge you extra for the mod. The car doesn't belong to you. They have to sell it after you turn it back, so would they be interested in selling a car that's been tuned? No serious buyer wants to buy a car that's been tuned by someone else. And Dinan's warranty or not - it doesn't void the extra wear&tear.