I, personally, can vouch for the K & N since the V70R is the 5th car that I am using it (car that I did or currently do own). I used it on a 1989 Ford Escort GT for about 45,000 miles, on a 1993 Eagle Talon ES for 85,000 miles, on a 1993 Ford Probe GT for 18,000 miles and on a 1992 Subaru SVX AWD for 23,000 miles. I noticed most difference in most cars (incl. the V70R that I currently own) except the Ford Escort GT. Most of the gain had been in the higher speed range and most pronounce in the Eagle Talon, Ford Probe and the V70R.

I am in no way an "admirer" of K&N, perhaps I have only used K&N because I have not had serious access to a better (if any) alternative. But I can say for sure, that it did make a difference, especially on my V70R, I can really tell when I push the car harder than normal. Perhaps it is also the dual (cat back) exhaust that I have, but I doubt that.

On any car that I used the K&N for a while, I never had engine problems, so I doubt that it can let in such bigger particles, enough to cause engine damage.

Yannis