Use some cleaning putty to seal the balloon, it works for sure !
Also use a 2nd ballon to be sure the 1st one will not get damaged.
Do not use an airfilter! If you are using an INSBOX just cut off the foamfilter so it can not run full with water and block the airflow.
In hard rain it is wise to be sure to keep temperature in the engine, place a sheet of lexan between the chassis and motormount so the chassis will not cool down the engine. Also use a smaller head or even some do not use a head. This head is from an airplane
I do not change a lot on the car, creating more roll by taking away the swaybar can mess up the performance of the car, the only thing I do is minimise the camber and loosen the srews which adjust the play on the rear swaybar. The extra play will give a small roll into the car but the swaybar will pick it up when the roll goes to far.
And when you have aqua's it is time to play !!!!