I love it but it does seem like it would block about 40% or so of the air flow. In the winter no biggie but a hot 80-90 degree summer day, you may want it off ?
I think possibly you can get a temp guage Chris to take the place of the oil dip stick, it would be interesting to have the guage on and run guard with it off and on, on the same day, just to see how much hotter it runs.
Something like this one
http://www.xrsonly.com/content/index...mart&Itemid=77
If your threads match that may fit (be pretty cool too!) as long as there are no obstructions close to the fill hole that would get in the way of the guage.
Some guys even make them for fairly cheap.