I've just gave a try to VUPlayer with 3.98a and tested the same track twice...

Deserted vaults by ltj bukem

- VBR 5 (I think it's V 5 vbr-new but not sure of that) give a bitrate of 151 k
- preset medium give a bitrate of 125k

well, what I want is ~130 kbps files....

NB: both are transcoded from a wv lossy ~416kb

It should have been

-V 4 --vbr-new = --preset fast medium 165 145…185
-V 4 = --preset medium 165 145…185
-V 5 --vbr-new 130 110…150
-V 5 130 110…150

Since you got lower bitrate with higher quality setting, you for sure used different tracks. Try more tracks (10+) and same for both settings and observe the average bitrate.

J.M.

Try converting to mp3 in foobar. Sometimes vbr-old / new give different bitrates, but v4 shouldn't be smaller than v5. The wavpack files won't affect bitrate by more than 2 kbit.