any guesses on how much my ladys will yeild

im growing white widow, blue widow and white siberian all from dinafem seeds. they are all from seed. in 20 litre pots using coco. i am using canna nutes and boost. i have topped and tied them all down to make them bushy. i am using 2 600w hps light and i switched 12/12 on the 1/6/11 so any guesses on yeild or advice on how to maximise my yeild would be appriciated also any guess to how much the small plant may yeild this was the top of one of the plants that i practised cloning with