For tuning your engine like for instance building in a Alpha N system, you'll need different injectors or a adjustable fuel pressure regulator.
In simple terms; more air means more fuel.
For my build up from a stock 2.3 to a 2.5 with MAXX Alpha N and a DTM carbon airbox , I also had to change my fuel quantity.
For this I chose to use bigger injectors.
With the MAXX system I am able to regulate the fuel quantity per throttle and rpm position.
But on this subject I just want to explain a little more of my findings of injectors.

On the left side is a Volvo 330cc and on the right the normal bmw 260cc

The stock 2.3 has 260cc injectors and a stock sport evo 2.5 has 300cc injectors.
So easy or not, just buy some sport evo ones.
All injectors we are talking about here a manufactured by Bosch
Once you drop in on your local dealer, you'll shock by the prize of those things.
So I went on and did a little research.
Volvo did use the same injectors too in their turbo engines.
They also had a 330cc version, wich was cheap and easy to source.
But quantity is one thing to look for.
You also have low and high impedance, duty cycle and spray pattern.
All injectors (260,300,330) are low impedance injectors, so this would work.
Spray pattern on the other hand I couldn't find anything about it.
So this I had to find out.

Spray pattern are alike

The Volvo (green) 330cc injectors I bought from a Volvo scrap yard, and paid €15,00 Euro's for them a piece.
Like you can see on the above picture, the spray patterns are alike.
I had them professionally cleaned and tested.
All tests where done at 3 bar pressure and the picture below shows the difference of a complete duty cycle of the quantity of fuel delivered from 0 to 10.000rpm

Left 330cc and right the 260cc

The Bosh numbers for the injectors:

0-280-150-357 - Sport Evo 300cc
0-280-150-804 - Volvo 330cc

All four 330cc on the test rig