What parts are responsible for producing torque?

Should torque always be pretty close to the hp of the motor?

What would bring the torque up a few notch on a 305? (I know, i know, should swap it for a 350, blah blah blah!. But i wont!)

And how do we determine what kind of gears to put at the other end to make it more efficient (no loss of torque/hp)

Thanks!