your asking the same question ive asked a hundred times, i just put 30lbs injectors in my stock engine, only a explorer intake and 65mm throttle body was changed on the engine, now with that being said ive also tuned my ECU to accept the larger injectors, but before the tune i did not notice what has been described to me in the past, like black smoke out the back, running so rich it burns your eyes!!!!!, well i tried this just to see what would happen the car now responds much better almost like what its been missing the fuel, the only thing with getting bigger injectors without adaqaute head flow, or intake, is the gas mileage sucks, but the tuning helps with that....check out Moates.net and look at the Quarterhorse tuner excellent!!!! enough said, overall if you go with 24lbs for now, you'll be fine, make sure you MAF can reconize 24lbs injector,if your not tuning the ECU