Never , ever, let your exhaust allow water to enter....washing, riding or sitting.
If it's running, it should never enter the exhaust.
When it's running, never let it enter the intake.
As far as torrential down pours go, mine worked perfect...tho I haven't tried to test that extensively.
The more water you punish it with, the more clean and lube and attention it deserves, thats all.
But it is ready, no doubt.