You do change the dynamics of the ball.
What I found was it will increase the overall reaction, as well as overall amount of flare.
By drilling such a large diameter hole, generally far enough away from the pin, you create a stronger amount of asymmetry, thus increasing the dynamics.
I used an .050 diff, med RG core, pin above the fingers 5 1/4+" from the PAP. drilled with just an 1 1/4" slug in the ball. We then mapped the track migration and basically where the ball wanted to start responding to the lane. After drilling the Turbo Switch grip, it increased the overall flare approx an 1/4" and the ball responded approx 5 ft sooner on the lane.
So hopefully this answers your question. It is more or less placing a strong weight hole in a strong position in relationship to the pin/top of core.
--------------------
Formerly BrunsRico
As posted by Steven..."None other than our esteemed JustRico!!"