The Waterboxer from the factory already has a cold intake, from the vent area on the side of the engine compartment. As for a better flowing filter the element for the Syncro has much more surface area and can also hold more dirt. As for KN systems you should also go to oil sampling as there are claims that these do not do well at stopping silica. For the Vanagon the largest performance benefit of these is due to the decreased weight of your wallet. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Mark Milby
Sent: Friday, March 27, 2015 3:53 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Cold Air Intake

With what seems to be the easiest horsepower gain, I continuously wonder and search for a good cold air/direct air intake.
Has anyone pieced together a K&N Filter system.

Just wondering.

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Mm