Manny Pacquiao was a skinny 17 year old teenager, fighting at the lower weightclasses, so him putting on 30 pounds in 13 years. With the right training and of course because Manny Pacquiao is amazing himself, i'd say Manny Pacquiao at 142 or ETC is about his peak weight now.
When Floyd Mayweather Jr was a teenager he was a Featherweight, plus when he fought ODLH at Jr Middleweight the max he coud get up to was 150.
Floyd Mayweather Jr isn't that much bigger than Manny Pacquiao IMO, and if Manny Pacquiao can take Miguel Cotto's best shots, and destroy Ricky Hatton in such brutal fashion, he is certainly no blown up Lightweight.
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