In all honesty, regarding horsepower, you most likely will not see any gains that you can actually feel. If you added a CAI and Headers (if they even make them for a V-6) you might tell a difference, but the cost overall wouldn't be worth it.
I have a 4.7 V-8 and wanted to get "True Duals", realizing that even after adding a tuner...it wouldn't be worth it unless I had a CAI and Headers (plus H.O. cams); and the cost in the end would be close to if not over $1,000 more, I ended up just going with a single in-dual out set up using Magnaflow. I already had a single side-exit Magnaflow. There wasn't much of a gain in horsepower going with the dual out (which I didn't expect anyway), but there was DEF a difference in sound from a single to a double, which is really what I was going for. In the future, if I end up coming across a used CAI and set of Headers at a good price and I have a little extra greens to throw around I might get them, but as far as doing "True Duals" at all...ever...I can honestly only justify doing it IF I already have done the first two mods and then by luck came across the mufflers I needed and did the exhaust work myself (since I already have a welder and will probably get a pipe bender in the next year.
I'm sorry to say, but there really isn't much at all you can do with the V-6 to make it faster (short of swapping it for a V-8) and would at best be able to only enjoy a custom sound system for your tunes and an aftermarket exhaust (to at least make it sound like a V-8)