In the roadster it may be just a case of enlarging the holes, but byes for the coupe you have to drill the plastic bulkhead cover. I removed this cover, then temporally fitted the bars in place, and then offered up the plastic cover to mark the centre line is from where the bars touched, with a felt pen marking the line front to back. Then I knew that the hole centres would be somewhere along that line. Then just used a bit cardboard to make a rough shape of the plastic cover and laid it in position on the bulkhead against the side off the bar and again marked the centre line. Then laying the cardboard on the plastic cover allowed me to pinpoint the hole centres. The rest was good luck!