I have a 502 with a thunder bolt ignition. I need to put a kill switch in the boat..do I just run it in line with the ignition key??

I just hooked one up not a thunder bolt but went ignition wire into kill switch then out of switch (other leg) to key will complete circuit

ya thats what I thought..just splice in the kill switch before the key on the positive wire right.??

I wired mine into the positive wire coming out of the key going to the ignition box. If your kill switch has wires made on it already chances are they are not as heavy as the positive wire going to the key. If so you will be reducing the wire size going into the key. Wire going out of the key to the ignition box is usually smaller like the size of the kill switch wires.