**UPDATE**
So this is interesting. I weighed my car on a truck scale after work and it came in at 3880 lbs without me, and about 1/4 tank gas.
On track night, I had:
Camaro = 3851.5 (no gas) lbs
5/8 tank gas = 71.4 lbs
Me = 160 lbs
Grand total = 4083 lbs
If I use the formula above, I get 444 HP at the flywheel. Considering ~20% drivetrain loss, that's 355 rwhp, which is almost exactly what I dyno'd the day before under similar temps/humidity. I'm assuming if the weather conditions were better, I'd actually be making a little more HP, correct.
Anyway, sorry for all the math, but I'm a physicist....I can't help it