a cold air intake kit and tune would be a good place to start for around $500.00 but if you really want to spruce old girl up a little you might consider the following list of just some of the mods i've done to my 2001 v6 . cai kit,65mm throttle body,true duel exhaust from headers back,aluminum drive shaft,3.73 gears with t-loc,zoom clutch with Steeda tri ax short shifter and a good tune on the computer.you have alot of options out there for performance parts for that 3.8 you just have to shop around for the best deals.a supercharger or procharger set up will run from $4000.00 to $5000.00 and depending on your set up you may need to upgrade your fuel pump,fuel injectors and maf sensor.i plan on going with the procharger at later time when i can afford it and with the good internal parts i just installed in my motor (Comp cam,roller,lifters,springs,bearings etc.) i should crank out about 350hp to the rear wheel.i'm already opening the hood up all the time to prove its not a v8.if you want to see old girl, go to the achives under show us your pics of your v6 and i'm there around page 7. have a good one Smil953 and keep me posted on your progress.
as much as i love my sixxer i agree if power is what you're after you're either gonna need forced induction or a different model mustang. Although that being said if you want it for it's awesome auto x ability basic bolt ons then tossing that money into the suspension, braking, and handling. Even with a 4.2 build on my friends '01 v6 it had trouble still keeping up with my old stock GT, but jesus that cam made his car sound good ^^