I have a brand new speedohealer still in the original package for sale. I bought it only to find out that it doesn't work with my bike. This comes with the Kawasaki I harness kit.
From Speedohealer website --->
On most modern motorcycles, with factory speedometer error being as high as 10%, even a modest sprocket gearing change can have the speedometer off by 15%. The sprocket change will also cause higher odometer reading, creating a negative resale factor for no valid reason. The SpeedoHealer is an inexpensive, convenient and very simple way to fix your speedo and odo. Compatible with all motorcycles with non cable driven speedometer.
Fits ALL Kawasaki motorcycles with electronic speedometer, such as:
-Ninja ZX-6R (2004 and earlier)
-ZX-636R (2004 and earlier)
-ZX-6RR (2004 and earlier)
*Note: the following Kawasaki models require the Universal harness kit:
Kawasaki ZX-6R (2005+), ZX-636R (2005+), ZX-6RR (2005+), ZX-10R (2006+)
The retail price for this is $109 plus $15 shipping. I'm letting it go for $75. You're saving almost $50 for a brand new speedohealer and you don't have to wait for shipping. The only thing is that the kit is for Kawasaki models.