I can't say.  Never check gas mileage, but it seems pretty much the same as it was before I installed the DR cam.  I run the guts out of the thing so mileage isn't something I pay attention to.  The small tank is kind of a pain.  I generally do two nice rides on a tank, then I fill up.  The Raptor petcock doesn't leave much breathing room so I try to never get low enough to use reserve.  I also like to keep my A/F on the fat side so I would be a poor measure of fuel economy.

My engine has all the add-ons available, including the 3 options available on the VM carb and Stage3 cam.  I get 60mpg across the board, excepting a series of 1/4 mi. and 0-60 continuous runs.