Put some rubber in the holes so the tank won't vibrate, and why did you cut the center piece (or is it underneath the bracket if it is then you can put a bolt or something to fix the tank)?
You could have used that to fix the tank because when braking and with vibrations from the engine/road - it tends to slip out of the bracket.
Haha, great - if you need any help don't hesitate to ask. And try to make the bracket as strong as possible due to the vibrations and the weight of the tank/coolant.