2003 Mustang GT project: Is it worth the EXPENSE

Where do I begin? I have a 2003 Mustang GT. I have a fenderwell cold air intake. Pair of flowmaster exhaust. All the money that I've spent so far has been put into cosmetics. Body kit, wing, rims, ect. My next step is to do performance upgrades, but I'm smart enough to find the stuff, just not sure what has to be there to make sure the upgrade works to its potential. For instance if you change the throttle body you should also then change the plenum. Right!? So here is the list of things that I plan on doing. Ill take any input of things that arent worth it and also if Im missing things that need to be done in addition to.
I plan on getting:
BASSANI 4602VC Ceramic Coat HEADERS
Mustang Exhaust X-Pipe w/Cat Bassani 46993BX
STEEDA MUSTANG GT 4.6 UNDERDRIVE PULLEYS
Complete Front and Rear Brake Conversion Kit w/Brembo 13" front and11.65" rear rotors
KONI Sport Handling Package w/ Lowering Springs,Struts, and shocks 1 1/4"
Ford Racing 4.10 Ring & Pinion Kit M-4209-G410
Accufab 4.6L 2v 70mm Throttle Body & Plenum Combo SCT Superchips Custom Eliminator 4-Bank Mustang Performance Chip{custom pretuned}
Venom High Performance Fuel Injectors 24lb
Venom VCN 1000 Nitrous Kit
This is pretty much my wish list, let me know what ya'll think about it. Any extra things that should get done on account of something else already being taken apart?