I recommend trying one on before you buy one, some one could probably recommend a race shop around you if you post in the local sub-forums.
Also be sure to check with whomever you plan on running with if they allow both M and SA helmets, or just SA. Also 2005's are out so you may want to look into those depending on how much you want to spend.
As Greg mentioned, if possible, try one on. A local autocross is usually a great place to see and feel a variety of helmet brands and sizes. As for using an SA2005, Greg is also correct - this is about all you'll find in a new helmet now, short of clearance items. It's a good idea to stay ahead of requirements.
Many autocrossers and track/DE participants prefer the Bell M2 (click). It provides great features in a relatively affordable package. It's a great value helmet. There are less expensive helmets, there are more expensive. All SA2005 helmets have met testing requirements, and the price difference will be seen/felt in the features, comfort, and weight.
Don't hesitate to contact us if you have any specific questions that are not covered in our Safety Products article, or in our Track and Autocross category.
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