Battery question

[George C. Paramithas]

Mine has seen better days and with the cold nearing its end I thought I'd replace it. 
Auto zone said $63 plus tax, I said this warrants research. Does a GTS need a sealed 
battery or can one go with a non-sealed type? I assume there's a way or there can be 
made a way for a vent tube to point under the bike but I wonder if Yamaha engineers 
had a better reason for going the sealed way i.e. overflow, acid vapors & the EEU 
comes to mind.

Thanks
George