Thanks Coastiejoe, but everything I can find on this subject says that Sparks with IBR, come with a GPS module which is integrated into the speedometer. Sparks without IBR or sparks with after market IBR, do not have this module and have a strictly RPM based speedometer.
It is so commonly stated on message boards that there is not any difference, other than IBR, when in reality, the GPS based speedometer is an additional difference.
As I do mods such as adjust my prop pitch, max RPM, etc, I would like to have an accurate display of my speed on the display, rather than having to use a GPS.
I would love it if I am wrong and can somehow unlock the GPS module in my spark, but I do not believe it exists.