I have used all the way up to 36lb injectors trying to find the rite combo for my turbo set up, but until its in boost it runs is if it was a stock 4banger. So from what I have experienced I would not go much over 24lb injectors or you will have a crappy idle, and it wont do you much good for power wise unless you go to forced induction.
Now with my set up i can modify my fuel maps and thus back off the fuel at idle so I could run really big injectors, but as i said earlier there would be no point as it is just overkill.