Now what application?

Bashing, racing, both? Which one do you do more of?

It's impossible to tell. Even for a thing like Sleepy does with his T4, there is not one perfect material. Carbon fiber is fairly strong, and extremely light, but making it is very hard, and couldn't be made into something like the tranny case. This is where plastic, nylon, comes in handly, because it is easily molded, and strong.