There are a couple of things to bear in mind:
Plextor drives don't report absolute jitter, only the relative level across the disc. So one cannot compare the jitter level of different discs using a Plextor drive. The only consumer drives that can report jitter using an absolute scale are Nexperia-based Benq DVD writers (or some early Lite-On CD writers). Production of the Benq drives ceased over 5 years ago.
As kg_evilboy has already mentioned, because the audio has been digitally encoded reducing the jitter level will not affect the sound quality at all. Some CD players have difficulty reading discs with high jitter, so it can affect the 'playability' of the disc and may increase the chance of a CD player encountering an uncorrectable error.
But the whole question of 'sound quality' is irrelevant to CD writing. Unless the drive playing the CD encounters an uncorrectable error (or has an inconsistent read offset) the audio data read will be the same.
There are two levels of error correction on audio CDs. An uncorrectable error is â‰¥3 bytes at the second level of correction, normally referred to as an E32 error (in PlexTools CU). Remember that these are errors reported by the drive, not errors which exist on the disc as such. Another drive reading the same disc may encounter more or fewer errors.