Nicotine in 100% PG can get irritating. 100% PG does the least to buffer the irritation and also makes weak vapor. VG dulls the flavor and nicotine throat hit and smooths the irritation while adding more vapor. Even 10% VG will add more vapor.
But I started on 100% PG. It did get irritating (some get sore mouth, tongue, throat, or even lungs). I switched to 70PG/30VG juices (I bought them that way) and then when I started using cartomizers I eventually switched to 10-20% VG instead (soaked in easier, made my cartos last longer).
If you add VG to your juice it will also dilute the flavor and nicotine strength. But you could add some. Just make sure it is 100% vegetable glycerine, not random drugstore USP glycerin because USP allows animal glycerine too which does not taste good for vaping. I wouldn't add more the 10% unless you need to.
I occasionally vape 100% PG juice now that my nicotine is lower, but not as one of my main juices.