If you really want low end torque at idle speed or just above idle speed put in a smaller than stock duration camshaft. This will maximize the fresh inlet charge trapped when the intake valve closes and therefore maximize low speed torque.
It'll reduce midrange torque and kill the top end. Probably not what you want but is what you asked for. If you specify what RPM you wish for torque peak that may eliminate my suggestion.
If you want midrange torque then suggestions made by other posters above are more appropriate. Compression is always good as long as you stay out of spark knock.
