Just changing the injectors anf throttle body wont give you any noticeable difference, you usually only change injectors when your engine needs more fuel like when you put a cam in or increase the engine capacity.
If you want more power, i suggest you look at the mace website and look at their range of plenum spacers, ported throttlebodies, and the like.
Do a search on here about the parts you might like from mace and you'll find an abundabce of info about the effects of each part and what you can do to get the most out of the mods.
Just remember if you change things too dramatically you'll need a retune or your car will run like ****.