We stumbled across this site when we were looking for something else. OBD tuning is by far the easiest way of tuning your car. Non OBD ECUs can be tuned and it may not be as difficult as you think and ECU tuning on older car can give you results better than you thought possible.
As the title says they are sites dedicated to open source software that tunes the car’s OE ECU. You need hardware for non OBDII/OBD2 cars but they are link to people who offer these services.
Here is a link to the link on the StrikeEngine directory for companies making performance chips and stand alone ECUs