Your 2002 V6 Mustang
is already equipped with the Split Port Heads and Intakes. The 1994-1998 V6 Mustangs are Single Port and a common thing for 94-98 V6 Mustang owners to do is to swap the heads/intakes and fuel lines from a 1999-2004 V6 Mustang into their 1994-1998 V6 Mustang. The Split Port Intakes and heads flow better and produce more horsepower.
As far as swapping a V8 in you will need to get a 4.6 V8 from a GT and basically the whole GT as a donor car. It's not cheap. I would go a different route.
You can do all the bolt ons on your V6 like your boyfriend recommended. A Supercharger is a good option but will set you back a good 2,000 dollars.
A popular modification is an X-Cal 2 from VMP Tuning Inc
which allows you to firm up your shift points, increase your timing and get a decent amount of horsepower and torque from it.
Welcome to the site and hope that helped a bit