How much could I HP could I gain from each alone and how much from the combinations of both? I have a 255lp fuel pump.. and the mods in my signature.

 

If you just have to do something, get your injectors cleanded and flow matched. Send them to Rich at Cruzin Performance http://www.cruzinperformance.com/ then take the car and get it dyno tuned.

You dont need larger injectors with your mods and you dont need the AFPR unless your setup requires fuel pressure greater than what the factory value is (which according to your mods, you don't).

In the end it is your money do what you want, but you will get better results from getting your injectors cleaned and flow matched and then getting the car dyno tuned.

 

Ditto.... you can push 400 flywheelHP with the stock 24# injectors. You aren't there yet.

Adding a larger injector than you need will not add any power. Your engine is "air limited" at this point, not "fuel limited". Altering the fuel pressure will not accomplish anything either.