Computer Car Management

I have a laptop permanently installed into my car. Right now all its only used for running my audio setup. I'm looking to hook it permanently into the OBD system. I'd like to be able to adjust fuel curves, ignition timings, monitor my nitrous tank pressure and capacity, run my interior and exterior neon lights and LCD's, etc.

I'm looking for a site with information on creating a great car computer. My car is a 1997 Mitsubishi 3000GT SL.

You may find different sources for your Mitsu, but in general, OBD2 editing software is incredibly expensive. Like for my car, OBD1 software can be found for $170 including the patch cord, but the OBD2 software is pushing $3000. Hopefully its different for your car.

Autotap often has a pretty wide selection of software... check autotap.com

if your laptop has a paralell port you ar in luck because you can use various "hardware hacks" to make it read inputs from various temperature sensors, pressure transducers, and viberation transducers provided that you use a signal that will vary between 0 and 5 volts. it is also possible to use the printer port, along with transistors that control the coil of a standard 12 volt relay, to control high power devices.

this link describes how to make a circuit that allows the paralell port to monitor up to five inputs.
http://www.geocities.com/huz_52/

and this link describes circuits that will allow input and output from the printer port for applications other than printing (how mundane).
http://www.epanorama.net/circuits/parallel_output.html

now for the bad part: you will have to learn to code, i hope for your sake you have a friend that is into that because it will make things a lot easier. if you don't then maybe you can contract a college student to write an applet that will allow you to display the port's inputs in a menaningfull eye-candy laden manner, and control the outputs by clicking a box displayed on the screen. hope this helps.

*edit*
here is a link to a site that supplies prefabricated controller boards for use with a paralell port. the price is light, they use 12v. DC, and they supply software that runs on win 9x and NT based operating systems.
http://electronickits.com/kit/complete/elec/ck1601.htm
i'm sure that there are many other companies that supply such hardware (especially for indu$trial aplications) so do a search if that one is not suitable. there are also usb compatible control units available but they usually fall to the expensive side of the fence.

now for the bad part: you will have to learn to code, i hope for your sake you have a friend that is into that because it will make things a lot easier.

Bad is somewhat of an understatement. Not only do you have to learn to read code, the code is in hexadecimal format. So its like earning your law degree from Chinese textbooks. Big words you don't understand written in complex characters that have no correlation to any language you know.

I have some background in Hex, some experience with computer code, and plenty of experience with tuning cars. I once saw a string of code from my OBD2 computer and it was like watching the Matrix.

it's not that bad if you use a high level language to write the code and compile it to an executable file. if you were to take any .exe and view it with a hex editor then it would remind you of the matrix, but if you read the source code then you'll get a vaurely human-readable version of what the computer's instructions are. by that i mean there numbers that represent data (maybe in hex or decimal and in the odd case octal) and there are butchered and abreviated human words (and their inbred and crossbread cousions) that instruct the computer on how to collect, manipulate, and display that data. however once the compiler is done processing the file it is all ones and zeros. here is the thing though, i know all of that from experience with trying to learn code, but i also like to do OTHER things with my life. that stuff consumes too much time for my tastes.