I was just browsing round MVPs site in the US, and it looks like they've finally got their clone of the old Fields harness available. This basically is a short bundle of wires with an ECU plug on either end. The idea is you can solder any electronic gubbins you want in to the harness on a bench, then just plug it in between the ECU and the existing harness, without having to hang upside down in the footwell cutting wires with 5cm of play in! Fields made the original one, but stopped a year or so ago.
Would be very handy for anyone installing RLTC for example, or other ECU gubbins. Too bloody late for me as I've installed mine now, but for anyone else they're available from MVP Motorsports for $275USD.