I would be surprised if just changing to a K&N filter did anything to boost HP. If that is the goal, CAI is the way to go on the induction side.

The stories about oil fouling the MAS are true - it comes from using too much oil spray.

I use K&N on a street rod with a carb set up - I read the directions carefully (don't usually RTFM first) and they were pretty clear about not spraying too much oil. I didn't have to worry about a MAS but didn't want to dirty up my carb either.

Just my 2 cents.