The other option is a Sy Klone pre cleaner which draws the air from underneath and also expels the heavier dust keeping the air filter much cleaner in dusty conditions.

I have always been concerned about water getting in with the ram style tops and have run Sy Klones on my last 3 vehicles and swear by them. With a Puma the larger head hits the roof requiring a spacer/adaptor but I know who a top bloke who sells them.

As this thread is starting to evolve. Can anyone suggest based on calculations etc, what diameter pipe should be used for a snorkel onbsay a defender 300 with the fixing on the wing side?
Or if anyone knows how to start these calculations without a flow meter please share them.
I also think the standard mushroom top may be restrictive?