I am considering taking out my standard exhaust muffler's cats, and replacing it with baffles. I want to shorten the cans by at least 10cm, just for the looks.
Are there any reason why I should not do it? I have the '09 model with the lamda sensor.

i see no reason why you cant do it by that amount but im no expert ,you might lose money on trade in if its noticed .If it was me i would get after market endcans then when you come to sell you can put orignals back on bike and sell after market cans but if youre set on doing it let the chopping begin

I to would go for aftermarket cans,doing what you are thinking may affect your warranty. Or insurance .

You guys are right, but if I had the $$$ for aftermarket cans, I would do it. I dont :-( so I am making due with what is at hand. I want to shorten them, so I can do a tailtidy mod, and fit indicators in line with the tail light. If I dont shorthen them, they are in the way.