In this case altitude will not affect top speed because it's rpm limited, the quad will reach top rpm regardless of altitude. And going to a 2 inch bigger tire only gets you about 2mph more
So you're saying that if 2 bikes; 1000 cc and 400 cc have the same RPM they will both have the same top speed. If the 400 has an RPM 500 greater than a 1000 it will go faster.
Please read the entire thread and original question
2016 High Lifter 1000 - GSE muffler and intake
2006 Raptor 700 - Stage 3 cam, intake, exhaust, tuned