Finally Jon, its good to see you get down to it!

Since this is 'installation notes' I'll help you fill in a few gaps:

The car has factory Bose. Rather than attempt to do anything as complex as a Bosectomy, Jon is using the 'Nexxia PC2-78-BOSE' adapter, as seen here:



It provides neat ISO and Line Level RCA connectors from the Mazda plug leaving the rest of the Bose bits working as they were. Its says it is only for the RX8 and 3/Axela Bose systems, but looks like it works for the MX5 as well