As far as I know, the 127 was shipped with the high/low band tuning (I know all of the ones I have were). The risk you face by going outside the shipped band is that the reception will be reduced. So, it's best to stay within the band. If your receiver is a couple years old, it's not a bad idea to send it to a service center (Hobby Services, Radio South, etc) to be checked and tuned. Send it with the new crystal and they'll adjust it to optimum performance.