Adding heated grips to my kz440, too much draw?

I'd like to add heated grips to my kz but I am wary about overdrawing current with the stock lighting system. How can I figure out what is too much? And is here something I should do if I add the grips to make sure they don't suck down power when not needed?
www.amazon.com/Tusk-Grip-Heater-Kit/dp/B...78/ref=pd_sbs_auto_4
I am thinking about using this kit

Any idea what the max draw is in amps? Does your bike have an accessory fuse box?
JakeWilson has a couple of installation links, but I didn't see mention of the power requirements other than that they are 12V. A TWTEX forum topic from several yrs ago indicated that they were between 36W & 48W or approx 3-4 Amps (I have no idea if the product is still the same).

Installation note from the TWTEX topic: if you can use the kit, you'll probably want to insulate the heaters from the handlebars so that you won't lose too much heat to the bars - either electrical tape or heat shrink tape.

I have Polly heaters on 2 of my bikes and am very happy with them - the PH400 kit is for motorcycles and they make a PH300 for atvs and snowmobiles - they draw 3 or less ampshttp://www.pollyheaters.com/ph15.htm