Originally Posted by Fabrik8
Some cars yes, some no.
Some cars can actually compensate for piggyback computers too. Depends on the car and the mods. Basically the ECU will try to make the engine run the way it knows it should. You can make more power, and as long as the ECU detects that the engine is running correctly, then it doesn't care a lot. You could use an AFC, CAI, ignition, and whatever else, and as long as it's tuned correctly the ECU doesn't know it's not stock. It's all based on the sensors, so if the O2 reading is within spec, then often it's happy. There are gross exceptions though. You'll have to talk to people with the same car and engine who have done the same mods..
Thanks for the input fabrik8 now here is another ? Do you think it is worth switching to OBD1 because if it is in probobly going to get my harness and p28 from you if you have one.