Axle backs are gonna give you the most change in sound for the lowest cost compared to going straight to headers. Youtube a bunch of videos and see which one you like best, that will change your sound significantly. Cams IMHO don't necessarily change the sound/tone itself, but the lope is addicting! and throwing down $800 plus install charges seems overkill just to get a sound you want. HP gains are seen with them as well. No doubt headers will too, but most longtubes shift the power. Drop off lower end TQ for upper end HP. Same with cams that actually are grinded for power gains instead of just sound or lope MOST of the time (there are exceptions). Then if you get, say, FRPP hot cams, and you decide you want to supercharge, those cams gotta go. Have a good idea of what you want before you spend loads on one setup and then change your mind.
Axle back suggestions: SLP Loudmouths, Corsa Xtremes, Borla Stingers, FR500S... I'm not a huge fan of chambered axleback for these 3 valves... just sound weird to me. Very 'tinny'. I wish I had the money for Corsa's or the FR500S... Both sound nice with no drone. Good Luck!
2010 Sterling Grey GT
SCT SF3/X3 Tuner
Tuned by Henson Performance