Best bang-for-the-buck? Nitrous. However, you won't be pulling on any Supras with just a bottle.

Also remember that you can only put so much power down to the front-wheels before having major traction issues on the street. I would sell all those bolt-ons and save up for a turbo. You can also do some mild weight reduction while keeping the car fairly tolerable for street driving.

Oh, and if you really want to beat all those cars out there I suggest you find a good lawyer. Penalties for street racing these days are pretty harsh.

Shingo

ps. Keep in mind that all the cars you listed (with the exception of the Jetta) will still be faster than you provided they have the same budget for aftermarket performance mods.