you have a npi gt...basically all the normal parts any mustang owner might consider...except you need to consider a pi swap..
pi intake + 15-20rwhp
pi cam + 15 -20rwhp
pi heads 15-20 rwhp
basically depends on how much you want to do...pi intake is real easy and will wake your car up above 4500 rpms..do 3.73 or 4.10 gears..just look around..you will find lots of parts for your car..