Hum,
Throat hit is a combination of factors...mostly would depend on which one you classify as falling in to.
Nic- scratchy feeling at the back of the throat, of course increasing this will increase the throat hit...dangerous to toy around really as I'd stick to the lowest possible nic level you are comfortable with.
PG- Again is a carrier for the juice, also has about the same effect on the throat as Nic. The higher the PG the more you'll notice the Throat Hit.
Vapor Production (VP)- More vapor, more throat hit....pretty easy to describe as the density of the vapor will result in a higher absorption of the ingredients.
Heat- Warmer vape seems to have a higher TH then lower temp vape. If you want to experiment you could play with a higher wattage (8-10 watts) or so. This may produce the desired results. Note that it will change the taste of E-Liquids though. Just a result of superheating the liquid.
Experiment really is how you find that middle ground, you could try an 80 PG/ 20 VG mixture to see if this helps. I suspect that it will change the TH that you receive.
Hope this helps