Hi mate,
Best place in the North IMO is Motorsport Developments.....
They can advise you what route to take.
It's not just Cossie management but more modern aftermarket management like Omex, DTA, Autonic for example. The aftermarket managements are more flexible than the Cossie stuff as only certain people can map the Marrelli stuff...
Look at this topic. It has a bit of info about EFI set ups. The car should drive a lot better and give decent fuel ecconomy if set up properly.
https://passionford.com/forum/viewtopic.php?t=111612