Will the addition of a flare increasing hole on a highly polished pearl ball decrease the length?  For example on a Columbia Violent Eruption or Eruption Pro Hybrid or some other brand of ball made for dried conditions.

I don't think he's talking about a MOtion hole, I think he's talking about just a regular weight hole. 

Will the addition of a flare increasing hole on a highly polished pearl ball decrease the length?  For example on a Columbia Violent Eruption or Eruption Pro Hybrid or some other brand of ball made for dried conditions.

A "Motion Hole" usually adds to the length AND adds to the backend.

His first line asks specifically about the addition of a flare increasing hole.  MOtion holes require a specific layout to be used, you don't really drill a ball and then just decide you're going to add one later.  I think he heard the term somewhere and got it a bit mixed up.

I'd say he's asking about Motion hole when that's what the title of the thread implies.