If so - so am I. I've had the K&N seal deform on a BMW motorcycle. The
filter seal was too big, when the airbox was clamped closed the seal
extruded from the seal area.

The deformed seal argument is BS.  Their seals are just as good or
better than the OE filter seals.  They do not deform when they get hot.
 Those guys are on crack.

The rest of the K&N "claims" is also BS.  You will get no improvement in
horsepower or mileage.  You will get a filter that you have to clean and
reinstall rather than just replace.

I realize this is an old thread but as it happens, I was discussing
this very thing with my mechanic today. I've read about these filters
on the forums and was curious. The people backing K&N claim a 3-4 MPG
gain in normal driving, and a HP or two gain in more spirited driving.
I was also intrigued by the "clean & re-use" aspect of these filters.

My mechanic (Wittler Auto here in Albuquerque) told me that in theory,
these filters might be a good idea, but actually, they have a fairly
serious drawback. The seal is made of a silicone material, and
according to the Wittler, they've seen lots of these filters with
deformed seals. Seems that the seals deform when they get hot, i.e.
the silicone gets too soft. Thus, when the seal is deformed,
unfiltered air gets through to the engine. Thus, they aren't too fond
of these things. He did say that *if they were made better* they might
be OK. But, they would cost a lot more, too. So, for the time being,
I'm skipping them and staying with the standard OEM type filters in my
530.

Karl Winkler
http://www.sandiastrings.com

Just wondering if replacing the stock filter with the above would noticeably
improve performance or sound.

Any comments?