I'm pretty sure it's a requirement there as well Alvin, they do seem lax in the enforcement of it however. Most guys can be seen pulling sweats on over their shorts in the staging lanes but I've been known to take a pass or two with shorts on.
I've noticed Bruno does his burnout in 2nd - I've done my powerbrake in 1st and just modulated the brake/gas to keep the RPM's in a healthy range while controlling the forward motion.