[ridelikehell]

Hey UT...
I've got an '03 V6, maybe I can shed some more light on the topic!...

Everyone so far who has recomended the DiabloSport chip is 100% correct, it's by far the best chip for the car...All the regular bolt-on's go well on the car (cold air, underdrive pulley, etc.) are all pretty decent...For exhaust I personally cut out my Y-Pipe and put in a custom 2.5" H-Pipe with 3.5" tips and MAC Flowpath mufflers and it sounds great...I would advise against Flowmasters on the V6 as they tend to really REALLY thin out in the high rpms...
By far the best mod to do on these cars however is swapping the rear end gears...I've gone with 3.73's in mine as well as putting in a T-Lok (the V6's don't come with them)...so those along with the chip is a good thing to do since the chip can re-cal your speedometer too...
Incase you're interested, my current mod list is as follows: Short Shifter, Custom H-Pipe with Flowpaths & 3.5" Tips, MAC Springs, 3.73's w/T Lok, DiabloSport Chip programmed to 91 octane, Cold Air, Strut Tower Brace, Subframe connectors, 25% UDP, Rear Sway Bar.

If you've got anymore questions I'd be more than happy to answer!
Good luck!