Going to be changing my sp's to Bosch # f1000-51773 ( oem) and I thought I might change my air filter too. Which one does everyone use??? My car is a '99 variant with 36k on it. I've heard the con's about k&n ( oil or not, no extra hp for $50) so I need some help.
I've used K&N for years and have never had an issue. I used to work at a performance import shop as well and we sold literally hundreds of them a month and never had a car come back with a blown MAF, atleast not in the two years I worked there.
My MAF sensor failed on my car as well, but it was when the car had a stock air filter, before I switched to the K&N. There are multitudes of MAF sensor failures that have been reported on this site, but I haven't seen any real evidence that shows the K&N filters are the cause any more than poor OEM parts quality, or general design life of the MAF sensor.
Still, I have to say that the K&N isn't all that wonderful, and I wouldn't recommend it. I haven't noticed any increased performance or mileage over stock. I have noticed a change in the car's performance when I clean the K&N - meaning that when the K&N is dirty (in my case it had about 20k miles) it degrades the car's performance. So I will likely clean mine more often, though the cleaning process is a bit painful since the filter has to dry after a water rinse and again after it is oiled. If the car is needed while cleaning the K&N a different (usually stock) filter needs to be put in temporarilly; this means you change the filter twice each time you clean the K&N. I don't know how many more cleanings I will do on mine; since I've already made the investment I will likely stick with it. But half way through the last cleaning process I felt I had made a mistake giving up the simplicity of running the stock filter.
I'd also like to add I ran a K&N in my 97 GTI fora total of 80,000 miles before trading it in. I never had any mechanical or reliability issues with it whatsoever and I only cleaned it maybe twice during that time. I did however notice much better throttle response, it was much snappier! I'd agree though that the HP gain was negligable and the gas mileage didn't change. I've yet to add one to my new Passat but wouldn't hesitate after running one trouble free in my GTI for 4 years!