This morning I re-programmed some Baofeng radios using the latest Chirp Daily Build.
Confirmed to be NOT compatible: firmware BFB231 and BFB251. You need BFB291 or higher. You can check this by powering up the radio while holding the ‘3’ button.
Confirmed, no issues:
Model no: / Firmware version according to Chirp:
GT-3 Mark II, N5R-213 / BFB297
GT-3TP, N5R3401 / BFP3-25
The actual effect on the squelch varies from model to model. The UV-82 and GT-5 for example stay more sensitive than the Sainsonic GT-3/MKII/TP versions. The latter are nearly deaf at SQ9.