Did you look at this one?
http://static.speedwaymotors.com/pdf/910-97710.pdf
They have some explantation on how the pulse signal is made. Its a bit confusing but it looks like which wire is hooked up determies the rating. I see 4,8,16k pulses being possible if I read this right.
Otherwise in the "speedometer" tab in HP Tuners you can alter the VSS output signal to 8 or 16 to match the gauges. Whoever did your tune should be able to make this change in about 28 seconds if his fingers are all broken.