Well so far my mods consist of:

PVC Home-Brew Intake (highly recommend) little more low end torque and a good loud roar from under the hood.

Line-X over the rails bed-liner (I highly recommend it $440 out the door)

Dual Exhaust system. I had the third cat replaced with a pipe, the OE muffler replaced with a 40 series 2 chamber flowmaster, and that runs out to dual pipes, the tips are about 14" long and about 3.5" in dia. (the sound is awesome, although, if your looking to low end torque I suggest leave the cat. I lost quite a bit of bottom end torque, but in the higher R's it screams)...........Later I gutted my cat and had the shop put it back on in case of warranty hassle. Although completely hollowed out it really quieted it up.

Autolite 3923 spark plugs. No big improvement, just wait until you need a tune-up
  
Clear corners (Euro style)

Showoff blue/white krypton 4300k headlights and fog lights. Not real blue at all, but they do light up the area very well.

Grill Insert made by Grille-Tech. On a scale from 1-10 I would say it's about a 7. But I just wanted something to protect my trans cooler, condenser, and radiator.

Adjusted TPS from .608 to .703. That was a noticeable difference. and worth the whole $0.00 and 15 minutes of time.