Mileage too high to supercharge?

good stuff. very helpfull. i have one more question. I have a friend of mine who has always been competative with me. He bought an 03 GT and kicks my ass every time we race eventhough i have more upgrades. why is that? before you say its the "Driver" i have an auto and he has a standard trans.

UPGRADES;
03 GT- BBK CAI, BBK THROTTLE BODY, BORLA OFFROAD X-PYPE.

06 GT- BBK CAI,62MM THROTTLE BODY, BBK SHORTY HEADERS, OFFROAD X-PYPES, DIABLOSPORT PREDATOR TUNE, ACCEL IGNITION COILS, BBK UNDER DRIVE PULLEY.
 
With those mods you should be walking his car unless he's not telling you something? Your's is auto 5r55s so do 3.73 gears and maybe nitrous but dont tell him about the nitrous lol. Also look into some lowering springs/lca's ect...
 
2003 Mustang

Dimensions
Curbweight (lbs.)
° Coupe: 3,006
° Convertible: 3,208
Weight distribution (%f/r): 57/43
Trunk space: 10.9 cu. ft.
Overall length: 183.2 in.
Overall width: 73.1 in.
Overall height: 53.1 in.
Wheelbase: 101.3 in.