I would hold off on SC, TC or juice until you try a CAI, tune and muffler. Most are suprised by the performance of the car after this cost effective upgrade.
Here is a list I usually reccomend for CAI/Tune combo...
CAI/Tuner Combo
• Doug/Bamachips: XCAL2 and your choice of TI or C&L CAI. (When I switched to his tune for my old TI, it shaved off 3/10ths on my time, his daily driver is an auto as well, though I think he has several test mules/test customer cars at his disposal)
• Evolution: XCAL2 and C&L (lot of guys use them, they have a good rep, actually met them at FFW, good bunch of guys)
• AZDynoChip: XCAL2 and ? (don't know if they do the internet thing, they will tune any CAI and produce some of the highest dyno numbers)
• Lidio/Alternative Auto: XCAL2 and CAI (I did some research and several shops referred me to him for Automatics, his personal daily driver is an auto)
• Brenspeed: XCAL2 and C&L (another highly reputable shop)
• Justin/VMP Tuning: XCAL2 and ? (Considered one of the top dogs for the V6 stang community and collaborates with Doug on occasion to my knowledge, he’s also tested more CAI’s on the same dyno session than anyone I’ve seen so far, read about it here:
http://www.v6power.net/vb/showthread.php?t=25551 )
Misc. Upgrades
-Axleback exhaust (MRT is the favourite and Scrming dyno'd it to show the highest gain, sounds kick ass in single configuration IMO, can be challenging in a dual configuration IMO but can be done)
-LSD
-Gears
-Tires/Wheels (Saleen, diversified and Casco have good deals on GT take offs, like others have said this is a good cost solution, I think diversified is the favourite around here.)
After that, if you still got the bug, put it on juice, SC or TC. Hope this helps.