As a general rule, you never make a contest of ST vs DX, HT, IQ, or any skill or secondary characteristic based on those attributes. ST scales with size, skills and other attributes do not. Instead, if ST is important to the contest, the stronger contestant gets a +1 to his roll for every 10% by which his ST exceeds that of his opponent. This rule is used whenever making or resisting any choke, grapple, neck snap, choke hold, arm lock, takedown, throw, pin, break free, or wrench limb; the contest is made using DX or Wrestling skill.
Choke, Strangle or Constriction: Damage is not equal to your margin of victory. Instead, you cause standard damage for your ST (see the ST and Damage house rule) modified for high Wrestling skill. However, instead of actually rolling a die, you do damage as if the die roll was 1/2 of your margin of success (round up), to a maximum "roll" of 6.
Arm Lock: Damage is not equal to your margin of victory. Instead, you cause standard damage for your ST (see the ST and Damage house rule) modified for high Wrestling skill. However, instead of actually rolling a die, you do damage as if the die roll was equal to your margin of success (round up), to a maximum of "roll" of 10!
Neck Snap or Wrench Limb: This is treated exactly like an arm lock, above, except that to perform a Neck Snap you need to grapple your foe by the neck.
Shake, Twist, or Roll: After any bite to grapple, you can shake your foe (or yourself, if you are smaller than your foe), twist, gator roll, or chew. This is a contest of DX or wrestling skill. If you succeed, you cause damage equal to your normal biting damage plus "constriction" damage (see above) if you won the contest. If you bit a limb or head, you do Wrench Limb or Neck Snap damage instead of "constriction" damage.