Post Photobucket reboot...........................
We covered this subject a while ago, and having discovered that the air filter is the same as the Series 1 Roadster, I had intended to change the filter for the 'as new' Roadster standard filter, then get a K&N in another year or so. But I've changed my mind!
Here's the original:
New K&N:
Detail of part number:
It slots in easily............
And back in the car.
I also bought a service kit - cleaner and oil, so when I do the Roadster service later in the year I can spruce the filter up.
UPDATE: I subsequently found that my Roadster shows a better Lambda reading at MOT time with the original air filter rather than the K&N. We've also more recently discussed the effect that oiled air filters may have on the Mass Airflow Sensor. I don't think there's a clear cut answer to this, but for the last 12 months my Roadster has been on the standard filter and feels just the same as previously with the K&N.
