When racing uphill, turbo cars are the best and mostly suited for the job; however when it comes to downhill. The race will be decided on who has the most guts and skill to cope with the danger of driving downhill. Because driving downhill is dangerous and even though you have plenty of power in your car. You won't be able to use it all when it comes to downhill.
So why is it that the car with a turbo will do a much better job than natural aspirated car. Because when driving uphill, the more torque in your car, the better. Also the more power you have, the better because your exit after the corner will be much faster. Naturally if you bring a car with no turbo againts the which has turbo. Then the turbo car will be thrashing the naturally aspirated car. Not unless the NA car has more power than turbo car and it has a perfect balance in that car.
With Downhill you need a light and agile car to quickly go through the corner. You don't need a lot of power because you got the gravity to push you down. Or should I say the inertia of the car when going downhill will provide adequate speed. Going downhill is a much tougher race when compairing with the uphill race because you are now going much faster and you'll feel more pressure because you're going downhill. There is a possibility of you falling off the mountain and god knows what will happen to you. It takes a lot to master going downhill because yo will need a lot of courage and skills to master going downhill.
Obviously if you want to trash your opponent in both session of uphill and downhill battle. You'll need a car that is light with plenty of power, good suspension set up, brakes, and a perfectly balance car. You see when you have a perfecly balance car, you have a bit of everything that I mentioned above. Naturally you'll have your uses for more power when going uphill and the lightness of your car will help immensely because you have more control of your car. Heavier cars are hard to control at the limit.
Once you have a perfectly balance car, you now possess a car which can go fast in either uphill and downhill. A perfecly balance car will do even better when going downhill because of the light weight and agility of the car. With the surge of power here in there, you have a car that is very competitive and you can challenge a lot of people who has a much faster car.