[LiM3y]

If you have a vert, you may be limited in who will let you track the car without a roll bar fixed.

The helmet should be snug enough that the skin on your forehead moves when you move it up and down or left to right without the strap tightened. If this means that your jaw hurts, try a different model. Any "hotspots" will just get worse in the heat and excitement of driving. Some model have different pad sizes to make a mroe custom fit.

Also, you don't need to spend $800 on a helmet. It just needs to meet the current Snell safety requirements