I think most vintage Merc owners can resist joining the "filter on a stick crowd", but maybe not all.
Visual inspection clearly shows that the cold air inlet systems on these cars are efficient and not fundamentally restrictive.
K&N filtration efficiency is highly sensitive to the amount of oil they contain. Too little and they hardly filter at all. Too much and they can gum up the air flow valve or MAF sensor. The OEM Bosch cellulose air filter element has lots of area, excellent filtration efficiency, and very little pressure loss. K&N filters are beat by about as many paper filters as paper filters they beat, and the very small differences aren't enough to make a signficant difference in actual engine power output. Where talking about a couple inches of water depression difference in most cases.
When people wax eloquently about the "washability" of K&N filters I ask why not wash out your old oil filter in solvent and put it back on. It's the same convoluted logic!!!