^^^Good point about spending money on safety^^^
Something I'd like to add though, about the difference between M, SA, open, and closed face:
Solo2 events only require a SNELL-M (motorcycle) rating. Both closed face and open fall into this category.
Solo1 and many On Track events will require SNELL-SA (Severe Application) rating.
Most SA helmets are closed face.
Something in the works at SCCA as far as open face versus closed face:
SCCA Technical Services issued an advisory that there may be an increased risk of injury from an airbag deployment when wearing a closed-face helmet.
Though, I'm not sure of any instances of airbag deployment in Solo2 racing.
If you're only interested in Solo2 AutoCross, I'd suggest an M-2000 open face helmet.
The added peripheral vision is a major plus, especially when you're just starting out.
And, if you can see
better, you're also going to be safer