Ok, a huge question...

This is basically the reason Im trying a low carb high fat diet. I would like to have all the benefits of a high fat low carb diet but I would like to have the benefit of high intensity fuel from carbs when that is needed. Carbs are the only/best fuel for super high intensity, right?
So...

Is it possible for me to a eat high fat and low carb diet most of the days and maybe even every day but when I want it and need it be able to eat carbs that will fuel my very high intense workouts/competitions (fighting).

Have you ever seen Fast and Furious, the car racing movie? You know the racingcars with a tube of nitro something in their cars, they drive on gasoline all the time but when they need really fast speed they push on a button to inject some of the nitro and the car can go much, much faster.
Do you get the idea?

Basically I want to keep my body as a fat burner but want to be able to fuel my body at the right time and right amount of carbs to get as high intensity as human possible when I need and want to.

I hope I made it understandable. I need these extreme, all out, high intensity bouts when I fight in 5 x 3 minute rounds.

Can I fuel my body with extra carbs for these high intensity bouts without changing my body from burning fat as the primary fuel?

Is this possible or how close can I get?