Another cure is to change the I.F. filters in your radio to those of a
narrower bandwidth. The stock filters are probably either 230 or 280Khz
bandwidth. If you change them to 150kHz filters (CF of 10.7MHz), your
adjacent channel selectivity will improve quite a bit. If you really
want super selectivity, you can install 110kHz filters............be
advised, though, that the more selective filters have a higher insertion
loss, and with the narrower bandwidth, both your distortion and your
stereo separation will be degraded.

Pete