remember that sway bars are tuning tools not a band aid for handling. They should be done last to adjust for under/over steering. If you want to get into handling a bit a nice pair of full lenght subframe connectors are a must. The maximum motorsports ones are a very nice piece and you will feel a difference. I have them and I'm about to install some custom upper subframe connectors for extra stiffness.
gears and a tune will give you the biggest bang for the buck too.
good luck... the modding bug is a terrible disease, but it hurts so good
EDIT:
a canned tune is a canned tune (even tunes from am are still canned tunes), your best bet is to be able to adjust your tune yourself. Get a laptop and data log at the strip (or a nice flat road). Really check out the timing at the rpm intervals, you can most of the time add about 2 degrees of timing on top of the canned tune. Since the companies giving you the tune have to account for tolerances in the 4.6 engines they still have a medium amount of safety in the tunes.
With a wideband you can get even more. canned tunes run rich for safety, and can effectually lean it out a to 13:1 which is what most dyno tunes are at. To give you some real data, my delta sniper SF software I tune with gave me a dyno run of 241/275 after I fine tuned for a while (at the strip using the trap speeds) I got 253/292. This includes UDP but they honestly don't do much...
I know its a different engine but the canned tune I had was running me at 12-18 degrees of timing and at 12.5:1 ratio after I tuned it a bit its running at 24-29 degrees and 12.9-13:1. The timing is the biggest factor, most of which was the compression ratio Im running. I believe sniper over compensated for the compression and reduced the timing a shit load, however, you can see the faults of canned tuning I hope. However anything is better then the stock tune, lol.