Engine How Much Air Is Too Much?

I've got a JLT CAI on my '06 Mustang GT with the SCT tune. I'm considering getting the GT500 Throttle Body and Steeda Charge Motion Control Plates in addition to underdrive pulleys. I know I'll need a new tune for the throttle body and the control plates, my question is with these 3 mods to increase airflow should i upgrade to larger injectors to increase the fuel flow? how much improved airflow is too much?
and i hate to ask this question as i'm sure it's been answered numerous times, but is the performance gain from the GT500 TB and control plates worth the $$? i'm running a stock engine w/ CAI and upgraded exhaust (but factory headers). want to get a few more horses out of the pony but don't want to go supercharger or nitrous, primarily just "backyard bolt-on" mods for my daily driver. sorry for the lengthy post. thanks for all reads and replies!!
 
Popular opinion seems to be to save your money on the TB, but charge plates will help a little. With where you are now, you'll be fine with the stock fuel system. You generally only need to upgrade fuel pump/injectors once you go forced injection.