What ever you do, do not waste money on a K&N for that motor.
You're 2.5 has the same intake system as a 4.0
4.0's do not have issues getting air, meaning your 2.5 has ABSOLUTELY no issue getting air and a K&N would do nothing but allow more dirt to enter your motor.
All of these mods are will have very little effect unless you get into the internals and do a cam swap.
Do a cam with a nice header and good exhaust and you will see some real gains.
Upsized injectors are not required for that little motor in stock form, and would just waste fuel. You can look at an upgraded injector like a bosh 3 nozzle type, which will provide a bit better atomization of feul.
Ditch the TB spacer, it provides no gain what so ever.