Default Google Now and Navigation do not use the preferred TTS voice

Hi all,

I've been playing around with the semi-new high-quality TTS voices, and I'd really like to use the UK voice for navigation and Google Now. Unfortunately, selecting other voices in the Text-To-Speech menu does not change either of those two voices (It does work in other apps, like utter!.) I messed around with INOVA as well, with the same problem. The only fix I've found so far is to change the entire default system language to English (UK), but that also has the effect of changing my clock to 24-hour, and a few other British tweaks that I'd rather not have, and it still doesn't solve the problem of letting me choose the British male voice (or any INOVA voice.) Any ideas?
Thanks in advance!

Almost forgot: Running Nexus 5, rooted, stock ROM +Xposed-- if there's an Xposed module out there that will do this, please let me know!