the 08-13 / gen1 bikes get their speed reading from the speed sensor on the front wheel. The gen2 and later get it somewhere else - not sure where tbh. Either the abs sensors (you'd think), but have also heard someone say it's measured from the engine somehow (e.g. crank position sensor, tho why idk).
Also the gen1 and gen 2 use different types of hall sensors for the (gen1) speed sensor and (gen2) abs rings, so unfortunately you can't really fudge a crossover there either even if you could make the pulses per revolution the same.
I don't have a gen2 bike so can't validate or refute the claim about where the gen2 measures it's speed but unless you're an electronics wizard this migh tbe better left alone.
I do however have a gen 1 and this is the signal output from the (speedo) hall sensor. Somehow you'd need to turn that 6 pulses per revolution of the wheel into whatever signal the gen2 istruments expect to see. Not trivial.