Altitude Compensation
Hiya
I hail from the coast in South Africa (Durban) there are many 503/582 motors flying here. As you may know Johannesburg is 6,000 ft above sea level. Without exception all owners that migrate to the coast change jets on arrival. Maybe post a thread in technical talk microlighters.co.za and advise your altitudes and you will get all the answers in fine detail. Also you will get other altitude power sapping mods the guys do.
I fly a HKS which has altitude compensating carbs (same as 912).
Good Luck
ZULU1