Make 2010 v6 mustang a better car?
1st mistake: You bought a Ford
2nd mistake: You bought a Mustang
3rd mistake: you bought a V6!!!
Ok in all seriousness: First things first. Do your bolt ons and maximize the naturally aspirated power. You have the right idea with CAI, bore out the throttle body, maybe a throttle body spacer, and a throaty exhaust. Make the car breathe better and your throttle response will vastly improve.
Screw turbo, get a supercharger. Way easier on the engine and can perform better in varying weather, unlike the turbo.
Tuners will do a number of things, it can remove a rev limiter, elongate your gears, increase top end speed. Do all of your bolt ons and internals (cam, pulley, etc) then its time for a tune. Look for a company that will offer a free retune to stock due to the fact that once your car is tuned your warranty is toast.
As far as handling? Strut bars, limited slip diff, performance tires (w rated or better), lowering springs, etc.
Don't forget cosmetics! Those new mustangs look badass with projo headlights and the rousche bodykits...