-31 will allow you to run higher boost when set up with the correct chip and injectors etc

2wd standard injectors are yellow

3 bar map will allow you to run higher boost when set up with the correct chip and injectors etc

ECU should be L1 if in a 3 door or L6 if in a sapphire. Take the lid off the ECU to have a look at the chip. A sticker MAY give you a hint if it's non-standard (along with the colour of the injectors ie light or dark greens). If you're unsure of the quality of a non-standard chip, get the car checked over/set up by someone you trust with experience of cossies.