Nice DIY, helped me do my own oil change today!
One problem I ran into, well one of a few, was that the small o-ring that came with the K&N filter would NOT fit with the base plate. I just could not get the plate to get over the o-ring and flush with the base of the center tube. This happened on both K&N filters I tried (the inner rubber seal of the first filter ripped in 2 when trying to press it on the center tube, yes everything was well coated with oil and was still too tight a fit). I chose to keep the old (~2500 miles) small o-ring on there, and it still clicked when I pressed the plate on, so I think the seal will be good.
Does anyone have advice for next time or know why the o-rings were so freakin tough?