Re: sequential transmission prohibited???
The rules for most sanctioning bodies running stock or modified stock cars, (SCCA, various historic racing groups, etc.) require retention of the stock transmissions.
In many modern pro series, such as the European touring car series, the standard box is replaced with a pure racing transmission, using sequential shifting and straight cut dog gears (a la motorcycles). These -- by specialized companies like Quaife, Xtrac and Hewland -- are lighter, stronger and faster sifting than most stock boxes, offer the ability to change ratios, and will handle much more torque an very high temperatures. These also cost well over $10k, which would represent the kind of "checkbook racing" most amateur sanctioning bodies want to avoid. These racing boxes would be as bad on the road as most stock trannies would be taking the punishment of racing.