Generally speaking, polish is going to delay a ball's reaction, thus, saving more energy and movement for the backend.
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I've only bowled 300, but I've benched 345

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bragbowlin: I agree with Gene that polishing will give it more length but
it will be saving more energy down the lane then hook harder off the friction.
You can actually alter your coverstock by sanding it in the direction of your track. It will make the ball go longer or just up the grit to like 1000 or 2000 which will make the ball roll slightly earlier causing it to burn sooner and having a little less backend. Try tweaking the coverstock to where you like it.