They are really different.  The Retro gives you more revs in the midlane and a sooner roll.  The original Piranha was best on the mediums or yesterday but today it would be regulated to dry conditions since the cover just isn't enough.  They did a good job Revamping the coverstock and core to give the same look on today's oil as the piranha's of old did in their day.
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-DJ Marshall
You're not Bowling if you're not using "B"runswick
Scratchbowling.com

I bought one of the Retro's in 16lb and loved the look I got from it. Then I dropped down in weight and made sure to get another one. Ball does read the lane nice and gives a strong but smooth movement IMO. I actually have it polished up right now for a little more length which has worked great also.

I also have a NIB one sitting at DougsProShop waiting to be drilled....that's how much I love this ball...3 in less than a year..
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The Dark Jedi Code
There is no peace, there is anger.
There is no fear, there is power.
There is no death, there is immortality.
There is no weakness, there is the Dark Side.

Great ball for controling strong backends, but imo was better on wood. Still styling lots of pop. this fishy was a tastey cracker!!
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Timothy @Juniors Pro-Shop
Montreal, Quebec.