2 inch pipe vs 2 1/4 inch pipe

I'm trying to determine wich size pipe will give me the best performance. The engine is a 360 magnum on the dyno its putting out 319 horse power and 424 ft lbs of torque. The engine is in a 91 dodge power ram four wheel drive truck, so i want the size thats going to give me the best torque of course. I have been told 2 inch exhaust pipe is ideal on a four wheel drive for torque, but i also been told 2 1/4 is better. Also need to find out what header tube size to run, i am considering 1 5/8 tube diameter or 1.625 tube diamiter, wich would be the best? would it be best to run 1.625 inch header tube dimiter with 2 inch exhaust pipe or 1 5/8 header tube diamiter and 2 1/4 inch exhaust pipe? keep in mind i'm wanting to go with the pipe and header thats going to give me the best torque and best throttle response.