If you want a fantastic solution to your OPUS ignition problems without replacing the original amplifier case so that you can win your competition, then do what I did and look at the REOPUS unit from Dave Curry. It's a completely redesigned PC board that fits inside the original aluminium case, even utilising the original wiring, pick up and coil.
After suffering ignition problems for months and looking at all the options, I stumbled on Dave's creation, which I promptly purchased after talking with him and being impressed by his knowledge and enthusiasm.
The results are absolutely outstanding with my starting, idle and performance issues totally solved.
I can totally recommend this unit, which is easy to install and keeps the car genuine.
Contact Dave on dcurryxtra.co.nz or if you want further confirmation, contact me directly. I can promise that it will be the best money you have spent on your jag in a long time