Thank you all for your replies.
Yes, it does have 160 HP.
Basically what is mean is:
Nowhere in the POH does it state it max. certified landing alt.
So does the "extrapolation is invalid" implicitly mean a max. alt., or does it merely state: there is no data for that alt.?
I personally think that a max. density alt. of 7000 ft is low, the plane surely must be able to do higher?
It's like the demonstrated xwind. It is not illegal to fly above the dem. xwind, just very stupid.
Thanks again.