Well, what he's trying to say is to continuie supplying fuel to the injectors after the rev cut limit. to increase it to whatever region that u want, using the remaining 2 sub injector wires from the harness. however, due to parellel connection with the 1 and 4 injector wire with the 1st subinjector wire, the 2 and 3 inth the 2nd injector wire, there might be current flow to the sub injector wire when the injector 1234 wire send signals to the injectors that could cause damage to the e-manage, that's why u need a diode. To prevent back flow signals.
Btw, something regarding reliability... The rev cut is there for a purpose... To make ur engine more durable. If u increase the rev cut(to gain more power), then u will have to sacrifice something else wether u do it using e-manage or ultimate or whatever....
Just need to rajin sikit service kereta... Kaka...