Default settings are choosen by the devlopers for a reason. If you're the kind of user who thinks posting spectrograms of mp3s is a good idea, you should probably should stick to the defaults.Are you happy now? Check the ABX tests. The encoded sample sounds better, more vivid and selective sounds, less noise.
I posted spectograms only to see the encoded .mp3 was not butchered by the encoder (trimmed from 20 kHz to 16 kHz), as you suggest with the default settings and so on.
May you tell me what is the reason the developers locked for general use the fine tuning (psychoacoustics) of lame v3.100? I remember in lame v3.98 these settings was available, not locked. Commercial reasons whatever?