About the handgrip heaters: If they go inside the handlebar, they have to heat up the metal before getting to the rubber grip. There are other options out there. Some go between the grip and the handlebar (I can't imagine this, as hard as it is to put a grip on the bar).
l.
Talked with my friend. The slugs that fit inside the bars work well for him. Take longer than the type that fit just under the grips to heat up, but once they do, he says they get quite hot. He said he didn't notice a difference between left and right, but felt it was because you hold on to the right firmly, while normally a looser grip on the left, (not all the time though

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I have the type that fits under the grips on two bikes. You need to get new grips as well at time of installation as on the old ones, the rubber has generally hardened making life difficult. Dual Star
http://www.dual-star.com/index2/Rider/heated_grip_kit3.htm sell great heated grips kits ($30.00) plus new grips at around $8.00, plus high temp. glue at $5.00, so not major money.
On the third bike, I have older Oxford grips that come built with the heater coils already inside a grip. These are more expensive but you don't have to assemble it yourself.
http://www.lockitt.com/AccessoriesGrips3.htm Haven't been at their site in a while, see price includes a variable temp controller as well. So maybe not that much more expensive. Although at 2amps max. per side, that is around 56 watts.
Chris