I never thought they did much, to be honest. With heated handgrips installed, they tended to keep a little bit of heat towards my fingers, but it was very minimal at best.
I McGuiver'd my Tiger hand guards with a $2 strip of vinyl baseboard and some velcro. It helped keeping the wind off and is better than stock. Need to figure out a way to cover up the bottom area as that's where the fingertips are.
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"Don't you know there ain't no devil, it's just god when he's drunk. "
— Tom Waits