There should be lettering scratched into the meter cover. STK = stock filter. Is the K&N an open filter or in the stock housing? If the housing is stock and STK is NOT on the Pro-M then that is the problem, and vice-versa.
1998 SVT Contour E1, Black 2001 Honda SuperHawk VTR1000F "I bent my Wookie" www.mamisano.com