Not sure on a roadster, but I tied in behind the passenger seat, just as my directions said. Just unscrew the plastic caps on the carpet and pull it down, and its right there, in the corner. Again not sure how the wiring is in a roadster, But my instructions told me to tie into a brown and pink wire, and when i found one and tested it, it wasn't wired to the switch. Turns out there were 2 brown and pink wires, so test everything b4 u tie in. So my lights came with a red and 2 browns. Tie one brown into the brown/pink, the other into the brown/gray, and the red into the black and yellow with white stripes.