Ok, i think i get what your saying. Computer assistance systems are really for EFI systems. If your getting into that style of car, you will be able to either use the factory system which will either reboot itself for the new data, or you will will have to modify it with a chip or a new system. As far as aftermarket comp systems, you may want to look into companies like MSD. Or you can wipe the entire factory system and write an entire new program. Not easy to do, but if your familiar with Assembly, it can be done.