Kill switch

I am putting a kill switch in my k11. It’s a rally build and just for safety if anything happens, was wondering where’s the best place I should wire it in
Any advice would be appreciated
An engine can continue running without the battery connected using the power generated by the alternator, so this needs to be disconnected in the same switch, bad obsession motorsport installed one on thier Citroen racecar and explained why it needs to cut both circiuts.