The Vararam is the worst choice for us in the Great White North
...its a snow sucker !!!
A guy from Calgary posted pics the first Winter he had his a couple years ago and the filter element got clogged and soaked after driving in a heavy snow storm.
Removed and sold shortly afterward at a loss, lesson learned.
I've had a K&N drop-in, Airaid and now a Volant with extra intake ram-tubes
...the Airaid and Volant were very close in performance and I'm sure the rest are similar too (aFe, S&B, K&N etc..)
Airaid did not seal tight to the underside of the hood, but the filter was HUGE!
Volant 100% sealed and had a port on the bottom for extra air tubes , Powercore filter never needs cleaning, no oil, good for 100k miles
and is very efficient, my track times did not change when I ran it with no filter at all, so I know it flows very well...
I'm guessing my newest K&N will kick the crap out of all of them
pic of my buddies install, mine isn't on the truck yet.