1. At a street meet it doesn't matter if you launch immediately after the light turns green or wait a few seconds then go, your ET will be the same (reaction time doesn't matter), so stage up, compose yourself, then go when you're ready.
2. Don't worry too much about the burnout unless you're using soft semislicks.
3. Try lowering your tyre pressure even more, with 255/40/17 i'd be trying to get more sidewall flex by going as low as 20psi, but its a matter of trial and error.
4. What mods exactly do you have? I would have expected 95-97mph from a car making under 150rwkw.