OK, I'll buy the "insurance" concept ... I was simply asking if anyone had any data to substantiate anything more than a sub percent marginal effectiveness increase ...
While I haven't done any research on aftermarket air filter systems, I have heard Pat Goss of Goss' Garage (syndicated radio talk show) note repeatedly that improved flow filters offer a very slight improvement (assuming all else is constant) ONLY at full throttle positions - he contends that the DO NOTHING at any other throttle position. Claims he has tested the ones that the manufacturers would provide to him.
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg