Originally Posted by CanAutM3
Your 2009 MY is in the category that will get the most benefits from changing the filter (by getting rid of that charcoal liner). However, 2-5hp is not something you will obviously notice from the seat of the pants. But all the small improvements combined together do eventually add up.
Yup, I have no doubt that it is performing better than the stock filter, but like you said, difficult to feel a 1% gain in power. I have ordered other bolt-ons (test pipes & pulleys) and can't wait to have them all come together along with a tune. Then I should definitely feel a difference!