I'm with slow. You get the injectors too big and getting the thing to idle right is a problem. The duty cycle thing goes both ways, you don't want 100% duty cycle WOT and you don't want them so big, that at idle they make the car run rich because the ECU can't set the duty cycle low enough.

What's the largest size injectors the stock ECU can handle? I know on Civic's and integra's it's about 310 (from a stock 240).

 

The next commonly available size is 440cc/min. The PCM can not compensate for them and you'll have fuel metering DTCs withing about 10 minutes of running.

 

Thanks.