@Plunderdrum Might try slightly lower flav % since you’re mixing 50/50 …more carrier (PG) more flavor. I prefer @woftam’s advice of just adding some distilled water to 70/30. For Sweetener maybe Pyure (has a little vinegar as a preservative) might bend that Grape into submission. EM (ethyl maltol=sweetener) also is famous for muting flavors …which might be what you’re looking for (muted Grape)
I mix for a neighbor who has a similar setup. Generally I bump up the flavors in a recipe by 25% and usually mix at 50/50. I use FLV Sweetness which is a Stevia type sweetener; seems to work well with fruits and it’s been designed as an eliquid additive.
I used to use Pyure but my bottle is over a year old and I hear that the formula has been changed (no more apple cider vinegar) so I haven’t bought any more.
Check out http://tjek.nu/r/3c0R.
Thanks for the advice, you guys! I’m going to whip up 2 or 3 testers with the different ideas from this thread.