I just finished checking the timing on my 03' SC430. I used a standard timing light that I connected to the #1 plug wires by pushing back the outer wiring cover so that the lights connector had more direct access to the actual wires near the plug connects at the valve cover. Timing after warming the motor was 10 degrees before top dead center 10 BTDC. Not sure yet how to change it, but no need since it's correct. BTW, if you have no check engine light, I believe the timing is correct, but you can still check it.