I would take a look at the horizon pearl, or maybe the mystic, those two balls would be farely close to the rs-1, but it still depends on how you drill it. Or you could try to find another rs-1, I have seen a few on ebay at times, you could also ask around if you haven't yet. Or better yet, you could take a look at the new roto grip illusion, that would be a similar ball.
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If your going to bowl...bowl for fun or go home