Yes, a mullen mouth pelham will make her pay attention more. However, if you are using it for jumping you have to take a couple precautions:
- don't snag her in the mouth!! Pelhams use a chain under the chin for control, so if you snag her, it does hurt them.
- make sure the chain is neither too tight nor too loose - if it's too loose while jumping, it can bang their chin and hurt them, or spook them (as I found out the hard way - my mare tossed her head before a fence, hit the chain, and did a sliding stop into the jump... aaaand of course I fell off.. of course this was when I was like 11 or something..)