Peter, made this for my current Roadster a couple of years ago
If I did one again, I wouldn't bother with the step-out, makes it more complex just to gain 1/2"
How did you get the correct measurement of the curve of the transmission tunnel?
You could make a cardboard template, and keep cutting it yo get the right profile. Of if you have one of those devices that mould to skirting birds or architrave, that would make it easier.