It looks to me like the 205 setup is designed to get the heat away from the turbo by the shortest route possible. If you add further exits on the bonnet, some of that hot air will pass to those exits too.
The 185 is a completely different scenario in that the air is meant to go IN through the scoop to cool the charge and then escape any way it can, including the louvres. The engine bay on a 185 is MUCH MUCH hotter than a 205, even with a CS bonnet (which also has air exits either side) where the bonnet vent works in the same way as a 205.
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