If you would like to upgrade your 2006 Yamaha factory handlebar hookers so they deliver heat all the way to the end of the hooks, the same as 2007 models, shuffle on over to your Yamaha store and ask for the Handlebar Grip Warmer Kit upgrade.
In true Yamaha fashion, your dealer will not throw a bag stuffed with heating elements, zip-ties and a tube of gorilla snot across the counter but rather a complete set of handlebars with hookers and full length heaters (and new grips) factory installed.
Better than this, the price is stupid. Normally, pipes, grips, heaters and hookers will ding your bi-fold over $130 (USD). You can have the entire package for a measly $29.99 (USD).