I checked those numbers before I went to the track and was obviously disappointed when I got my 1st time slip. I have heard 3:91 gears work best with the 380 horse crate engines so I wasn't expecting a 12 second pass but thought for sure it would run in the lower 13 range. I'm not sure lower gears and a converter will get me anywhere near 12.09. When I had my 73 pro street cuda I switched from an off the shelf 10 inch converter to a custom built 8 inch ati and picked up about .6