No the K&N problems are coming with brand new drop in filters. Also happened to my Infiniti QX56, I had put a drop in K&N filter in and in less than 10k the throttle body was all oily and gooped up. K&N is overpriced and over rated.

But now my R2C, made a deeper tone, a little louder, yes I get the swoosh or squeak as the filter tries to suck air into itself. Not sure where that squeak comes from, lots of ppl say the after market filters do that, I have an 06 G35 6MT, mine made that sound with just the factory airbox also, it wasn't as loud but still made that sound.....some guy asked if I had a turbo b/c it sounded like a blow off valve. In a way maybe, but I think he was just some young kid trying to look like he knew what he was taking about. I totally stand behind the R2C, it has been a wonderful product. Sound and butt dyno wise I think it was a great purchase.

 

^u sure it was the k&n that made the TB dirty and not from the plenum. cus TB will get dirty no matter wat