ignition cutoff 2003 corolla

i am thinking of putting an ignition cut-off. which wire should i cut the blk w/white or the blk w/yell. or both? i hope it's not both.

you were right blk w/white stripe is true ignition. as far as someone telling you that using an igniton kill is amatureish. well i wanna thank them. because in my younger days. of auto theft if it only had a starter kill, all i had to do is push start it, or if automatic open the hood and with a screwdriver start it. so i choose to go with ignition kill, much safer and harder to defeat. although nothing is 100% fool proof JMHO.