Swap V6 mustang engine and rear end or buy bolt on's?

I have a 2002 V6 Mustang and like every other true american teenager that has a muscle car im horsepower and speed hungry. So far I have a Bama tuner and a K&N cold air intake and was planning on getting a BBK 65mm throttle body, dual exhaust, and a 2002 v6 mustang procharger 9-11 psi. Would it be better to spend my little money on that or save up for a cobra engine and swap the computer, rear end, cable harness, ect??