A K&N filter is reusable (that is it can be cleaned, re-oiled and re-used many time over); so even though one might not notice any performance gains, at least it saves some money in the long run.
When I recently installed the K&N filter in mine, it did seem to add a little bit of performancce (maybe just hopeful/wishful thinking), but I can not quantitatively give you by how much.
On installation becasue I had to remove the air hose from the manifold throttle body, I noticed that the insides of manifold throttle body, where the throttle butterfly is located at, there was a lot of accumulated black residue/soot. I tries cleaning it out as thoroughtly as possible (by sticking in my finger with cleaning and de-greasing solution on a small clean cloth and by opening the butterfly) when I had the air hose off. Maybe I should have had tried taking the manifold throttle body off completely to clean it beeter. Has anyone tried to clean this part and how did they do it?
Cheers,
Danny
1970 280SL silver Euro 4-speed