Use the flavor at a lower percentage and then use smaller amounts of other flavors that have similar notes to enhance the flavor. That's basically recipe crafting in a nutshell. It requires a great deal of flavor knowledge. Very few of the flavors that we use are suited to stand-alone vaping. If you're looking for a simple solution, there really isn't one.

Never recommended percentages. They’re always inflated

You can go lower depending on your preferences, otherwise you could add something sour in small percentages

It’s good flavor but taking it to high 4% is pushing it. Could always use a little cotton candy to mute it some. It’s a great additive to other grapes like INW and FLV.

This may or may not work in your favor but bitter counters sweet, sometimes it's a null each other situation, other times it will add bitterness that's nasty, a very small amount might work. Bear in mind that this is a trick for nullifying the sweet inherent in VG in tobacco recipes, where a little bitterness is not so out of place.

As I said, it's a shot in the dark. It might go ok, it might go really horribly. I would try it though just out of pure curiosity. Grapes do have a tiny bit of that in their nature, so it might fly. Start way low.

Otherwise you can only go lower and build around it with similar flavors.

This also assumes you have FA Bitter Wizard.

If you don't, I could try it for you as I have both.

What’s the recipe?