I have drilled several balls with this core, both for me and costumers... Since this is a asym core it really depends on what you want it to do. As a benchmark ball i would proberly drill it 45 VAL x 4 1/4 x 55 MB this is if you are speed and rev matched. if you are slightly speed dominant subtract 5 from both VAL and MB angle and if you are slightly rev dominant add 5 to both VAL and MB angle. If you need more forward roll for flatter pattern so it wont jump add about 1 to 1½ inch but keep the angles and if you want it to store axis rotation so it really hooks of the back of the pattern subtract about 1 to 1 1/4 inch but still keep the angles.