According to Yuasa
http://www.yuasabatteries.com/yuasa0...2006yuaapp.pdf
their YTZ range are all factory activated and are the only versions which are suitable for installation in any orientation. Read the blurb and decide for yourself though. Might be worth contacting them to confirm.
I have a YTZ10S in a Deauville and it is a little gem as far as starting goes. The 10 is physically smaller than the stock curvy SV battery, the YTZ12S is about the same size, both have much higher cranking currents than a stock unit.
Reasonable prices here
http://www.inter-bike.co.uk/inter-bi...numperpage=500