Until you remove the retriction (the heads), bolt ons aren't as good as the ones on the 5.0. However, good stuff to look at:
Throttle Bodies-stick w/ 70mm since the 75mm screws w/ the AF ratio and won't be better than a 70mm. For a cheap one, go w/ the Explorer piece since you can get that I think for $90 at the parts counter (though I'm not 100% sure it's 70mm but that's the word on the vine).
Plenum- Trickflow, Accufab, and C&L.
Programmers- Diablo or SCT.
Exhaust- Cat-backs and mid-pipes won't net you anything worth it unless you get some headers, in which long tubes are the only ones worth the trouble. For headers, MAC, Hooker, Flowtech, Hedman, and BBK all makes LT (I went w/ Hookers) but I hear good and bad for all of them so it's up to you.
Shifters- Steeda, Hurst, Pro 5.0, B&M, and MGW are all good and basically the same so get one that fits you (style wise and knob placement).
CAI- Useless. Just remove the silencer and slap a better air filter on.
Gears- 4.11 are popular and brands to look at are Richmond, FRPP, and Motive.
Intake manifolds- hiperformancesolutions.com has a nice piece that fits w/o mods and Trick Flow has their piece too (useless unless you got ported heads).
For numbers, expect around 10hp for plenum and throtle body together, 20 hp for long tubes, and the usual for underdrive pullies (Steeda is the best). Also, consider beefing up the suspension (lower control arms and subframe connectors to start).