Mustang Aluminum Driveshaft I Got A 02 Mustang Gt An Wanted To Know Should I Get A Shift Kit Or A Aluminum Driveshaft?

I got a 02 mustang gt an wanted to know should I get a shift kit or a aluminum driveshaft? - mustang aluminum driveshaft

I already have a Diablo tuner, 3.73 gears BBK cold air intake, 70mm BBK throttle body a horse Underdrive roles. Who best fits my car?