Is it true that there is a measurable and defined performance gain using those type of filters compared to a regular paper ones? Obviously, K&N state that there is but how much comapred to a cheapo air filter? Anybody?

Not enough to tell if any.

Amsoil eaa



K&N sucks (IMO)

Welcome to the club grumpyoldmen!
As for filters (air/oil, etc) OEM all the way! Keeps you from getting too grumpy.

I just installed a K&N in my RX400H and I haven't had it long enough to see any mileage change. I did however have one installed in my old SUV and I did notice better throttle response(Seemed like more power off the line) and a small improvement in mileage(1 to 2 MPG). Best thing is I can clean the filter with dish soap, then reoil it and never spend another cent on replacement paper filters.