I fitted a replacement ECU from RPI a few years ago, had to change the whole unit as the chip in mine was not removable. I also fitted a set of their plug leads and their replacement ignition amplifier to replace the original Rover unit on the side of the distributor. Don't want to tempt fate but this is the only component on my engine that has has ever failed. We only spoke on the phone but the guy is very knowledgable if a little eccentric? The changes improved drivability and have been reliable.
