i think if you are not a dum dum and run through puddles like an offroad vehcile, it wont happen to you.

and once that motor tries to compress water it will blow something up due to the fact that it is trying to compress something that simply cannot be compressed regardless of the transmission.

bolt on do help but it matters for what type of engine and the application.

a local accord bolted on a intake manifold spacer and it dynoed 5hp and 5tq with bolt ons. so small things do help.