Just opting for a shock off a larger capacity bike wont give you a better or even equal performance shock. Most standard shocks are pretty crap out of the box no matter what they're size or manufacturer, for instance one of the best mods you can do to an FZS1000 in fit an R6 shocK.
Manufactures tend to buy as cheap as they can many don't last more than 8k and there past their best, even lower the std shock fitted to the FZS is one of those.....I kid you not. There're a few exceptions and certain manufactures have traits to how they set their bikes up out of the box.
Your best bet is to go for a quality after market shock these range from eye popping expensive to cheap and nasty. It depends what you want from a shock the two that tend to have good press are Hargon (£300 - £425) and Nitron (£330 - £460), I've fitted both and once set they are night and day compared to the std shock.
