UL
I won't promise my house as a warranty, but you can be pretty sure of this as real world numbers. 161 knots TAS @ 8000' on 34.5/35.5 LPH.
Oddly enough my calculations are spot on with the claims in the content you posted. I assume Vans have published that somewhere and I have never found their numbers to be inaccurate. They do not sem to be like the days of old where manufacturers would publish all sorts of claims that could not be realised.
Having said that it took two Aussies to sit in the Beech sales room and point out their G58 Baron specs were horribly ....errr...mistaken. Not all that long ago I am told.
So what are you going to build?