Maybe but it may mean changing a lot of capacitors.?
Please note the bandwidth is only part of the picture. One must also consider the shape and degree of its rejection. A smaller bandwidth at the 3 dB points might have very little difference at say the 40 and 50 dB points? also reducing bandwidth may add distortion to the signal.?
With a suitable audio dsp program like spectrogram you can observe the shape of the filter by just receiving noise. The stock qcx isn't bad.??
I believe the Audio filter is the one designed by Dave Cripe, NM0S, so you can get info on how to adjust the parameters from the documentation on this link:
Brent DeWitt
Daniel Conklin