+1000m (3281') altitude = -10% power, that's our rule of thump.
As your Agi has a carburetor, it may also suffer from too rich mixture in altidude, leading to additional loss.
To avoid running too rich, you could choose the jets a little bit smaller - but then lean mixture and power loss in the lowlands.
So that's only applicable for people staying for a long time in the same (but very much different than before) altitude.
I won't change anything.
My Xciting (old one, with carb too) has no problems from my home at 88m (289') sea level up to Nufenen Pass at 2478m (8130').