Is it a bad idea to install the trd supercharger to my automatic transmission scion tc?

I'd do some serious thinking about it. Find some online boards that talk about it and see what people say who have done it or why they didn't. Make sure you find some who have had one in for a while to see what they think after they've had time to really use a mod on the car. I make a point of never being one of the first people to "test" mods on vehicles. Especially major engine work.