The biggest issue is lack of parts such as the Throttle Position Sensor. I still have some, but there are a TON of aftermarket ones that say they are correct but they are not. They appear similar externally, but the curves inside the sensor are different. The Magneti Marelli used a PF4C sensor, and many people have tried the PF1C sensor. Because this is an Alpha-N (TPS/RPM) system, the curves inside the sensor are very important to fuel and spark timing. So when people buy the $60 look alike sensors and they struggle with getting it running correctly - especially at low to mid rpm, that is why.