A y7 makes barely over a 100hp? 5psi would be about a 30 something percent increase in power.
240cc are fine for 5psi on the y7 IN THE RIGHT HANDS.
Greddy kits ran stock injectors on single vtec cars with that low of boost.
Engine management is important though and you need to know what you are doing.I had my injectors cleaned/checked and ran them for a long time.