We are using 80/20 pg/VG we ordered these from mount baker vapor. They are extremely rough on the throat. So next time I was thinking of ordering 65/35 ratio. Would that take some of the throat hit away.
Yes.
Higher VG = more vapor, thicker juices, gunks up wicks a little faster, a tad bit sweeter, smoother throat hit
Higher PG = thinner juice, harsher throat hit, less vapor Does lower pg ratio make you have to draw harder? Does it burn your attys out faster?
I've never noticed any difference in how hard I have to draw despite higher or lower PG levels. My main preference is a 50/50 blend.
What would be the difference between 65/35 to 50/50 and what are some of the disadvantages of running 50/50 over an 80/20 mix?
See above.
I am running now Halo Sub zero flavor on a 1.8 ohm on 3.8 volts. I'm not sure what the pg to VG ratio is but it still irritates my throat.
You never said what nic level you're vaping. A higher nicotine amount also tends to give a harsher vape. Since you're just now starting out I would recommend staying at an 18 or 24 mg of nicotine until you're off the analogs for a bit. Then, if you want to you can begin lowering your nic levels.
What would be the best voltage to run a 50/50 liquid? I can only go up to 4.2
Depends on the juice, what resistance atomizer you're using... You say you're using a 1.8 ohm coil so I'd start at around 3.7 volts. Vape. If it's not quite what you're looking for, turn it up a little. Vape. Lather, rinse, repeat as necessary until you get a slight burnt taste. Turn it down just a touch. That should be the sweet spot for that juice. Each flavor may need a different voltage. In my experience I find that fruit flavors like a lower voltage while bakery and coffee flavors like it a little hotter. YMMV.
Good luck!