Don't mention lowered compression.
No, not required anymore, but it does mean running extra ignition retard to cope with the higher compression.
You could probably lose the piggyback controller and the fifth injector setup, retain your decompression plate and have it mapped on the OEM ECU with uprated injectors. Retaining the decompression plate would mean that Courtenay's would be able to run normal levels of ignition retard/advance. Would at least mean that you could rule out the fifth injector being the problem on your setup and then normal diagnosis would apply. Certainly haven't heard of anyone in the VX world suffering this problem on the original style conversions though.