During a med-speed typical pylon lot autocross, you want to avoid shifting so you won't disrupt the driving and transition of the car. On a hi-speed road course you have more time in the straights (although some may still be curved straights) to aford the shifting. A manual trans will allow more power to be used, whereas the automatic does take some away. Regardless which type of course you're on (med-speed r hi-speed), and which type of trans you have, you want to avoid disrupting the flow and steadiness of the car if/when ever shifted... try to concentrate on being smooth. My 727 has been bullet proof and it shifts fully automatic or manual up/down... I can trail brake more easily with an automatic, but manuals take more skill to master their advantages. Winners can be either trans (auto or manual)... the nut behind the wheel makes the final decision on how well the car finishes.