P2M upgraded 550cc injectors are direct drop in for RB25DET motors. The injectors were designed from used Japanese JECS injector cores to keep the cost down. All injectors undergone internal rebuilt and are flow matched & flow tested before shipping. The injectors retained the stock high impedance feature which will not interfere with ECU operation. All injectors shipped will be supplied with a flow chart showing the flow pattern for each injector in the kit, and will be as closely matched as possible to the rated capacity. Injectors comes installed with new top and bottom injector o-rings.