Looking through Max' source code I found this in MP3SettingsSheet.m:
CODE
Quality 40, Fast mode (-V6 --vbr-new) (~115 kbps)
Quality 50, Fast mode (-V5 --vbr-new) (~130 kbps)
Quality 60, Fast mode (-V4 --vbr-new) (~160 kbps)
Quality 70, Fast mode (-V 3 --vbr-new) (~175 kbps)
Quality 80, Fast mode (-V 2 --vbr-new) (~190 kbps)
Quality 90, Fast mode (-V 1 --vbr-new) (~210 kbps)
Quality 100, Fast mode (-V 0 --vbr-new) (~230 kbps)
Which pretty much verify that its using "-V2 --vbr-new" for its Transparent setting.