I dont know what a 155 is but I have caught a few cats in 120's by the head-couple big ones too-all lights out.No struggle.
I would never set a bodygip smaller than a 280 on purpose for cats.Too many refusals.
I have caught plenty in 160's set for civets. Some by the paw, some by the head. If the bait is real close to the triggers usually they're neck caught. (I'm using these MB skunk-killer 160's with the extra kill bar).