right now there is not to many options out there. a few companies including edlelbrock are coming out with aluminum 4.6 intakes. so for now i would get a plenum and 75mm tb and call it a day if you insist on intake mods.
personally i think you should put your mod money elsewhere. gears are the best bang for the buck. with a auto don't go less than 4.10's then i would consider other trans mods like j-mod or handheld tuner and at some point a torque converter.