From what I know, it's legal. I've had the lexan in for a few years now, and it's worked well. It should be braced, or it will vibrate. I've also had good luck with tearoffs on the lexan. Got tired of replacing cracked glass two years in a row.

I wouldn't put lexan on a street car. I used a tearoff for a year on a street/DE car, and it worked pretty well. Kept the glass nice.