Brake Upgrade Round 2
 

To get the larger hole centered correctly, I first traced the circle using the bracket as a template. Then I took a compass and drew a circle the same diameter as the hole, marking the center clearly. I cut out the paper and taped it to the firewall, centering it on the tracing. This gave me the center of the larger hole:

http://i1292.photobucket.com/albums/...pshvfkk4jh.jpg

Then I drilled it with the appropriate sized hole saw.

http://i1292.photobucket.com/albums/...ps3jsmmtyq.jpg