Wasn't trying to do that at all. Just pointing out that the Stihl products I buy come from North East Stihl, and they know the trees in my area and feel the 290 will cut faster with .325.
FYI, I run a 3/8" on my MS260 BUT I run a 16" bar with a sharp sharp chain and I'm not a bucking spike wrencher!!
I had a 361 and to put a .325 on it would be an insult to the saw for most applications. Not saying that some 9 or 10 pin .325 sprocket with the right chain couldn't cut cookies faster, but for real world cutting, give it a 3/8"!