Well, you can either do resistors or just go ahead and load your blinker circuit with all LEDs. Since LEDs draw so much less current than regular incandescent bulbs, it tricks the blinker regulator into thinking that there is a bulb missing--hence not completing the circuit at the specific amperage. I put all LEDs in all blinker lights in my truck and it blinks normally--and looks badass too! I just don't like having to splice into the factory wiring harness to install resistors. You can do it either way---all LEDs or add resistors.