Double Turbo and damage modifiers order?

[B1ackspidey]

Say I have a pokemon with an attack that cost two colorless and does 20 damage with a double turbo attached and an attack modifier (choice belt, cleansing gloves). And I am attacking the correct pokemon for the bonus to be applied (V pokemon or psychic for these two). What is the order of effects applied? Always though DTE applied first bumped it to 0 and then you couldn’t add from there. Or does it happen all at once so it adds up to 30 damage?

Thanks for any help.

 

[PokePop]

Any effects that are resolved during the same step can be done in order of the owner's choice.
So both Choice Belt and Double Turbo are effects on the Attacking Pokemon and are resolved in step G.2 of the Attack steps.
You can add the Choice Belt damage first and then reduce that.