X-pipe or H-Pipe.. Along with mufflers. Do alot of research on what you want your car to sound like. Personally, i like a raspier v8 that his bite. not bark.
so a
flowmaster muffler with x-pipe would do it for ya.. USE THE SEARCH FUNCTION to find a forum regaurding this issue. it will have 150 different combinations of mufflers and pipes. Decide from there. (Ignore what ppl say, its your f'in car. You choose how it should sound)
If you choose an offroad H/X pipe (ie - no cats) then you will need a Tune, or MIL 02' sensor deletes. otherwise your car will detect the missing cats, and run like ****.
4.10 gears will allow you vehicle to accelerate much faster. But Expect your milage to DECREASE on highway as your RPM's will be much higher.
if you've ever played a race-game. when you want more accel, you increase your final drive ratio (which is what adding 4.10's to do) great when want a good time on a strip, or a technical road course. but impracticle if your a highway driver (Unless your prepared to pay for the increased fuel)
Lastly, Have a good mechanic install your gears. If their not done right, they can whine.. Which can be annoying going down the highway.
Other then that, enjoy.