[engineer9]

Well, the area I hammered was about 10" wide (on the curve) x 12" long starting about 6" to 8" back from the face of the firewall. The larger the area you hammer, the less noticable the "bump" will be in the carpet inside the car....can't even see it on mine. I used a small sledge hammer with a big head to avoid getting alot of small dimples in the metal. The maximum increase in the tunnel height that I hammered in was about 3/4" at the center, which produced about 1/4" clearance when everything was bolted up.