Maybe I did not explane myself right.
Yes I know to see the aircraft you have to have it installed.
But what I want is to see a differant aircraft than the one the other player is flying.
Let me try to explane this way;
Say there are two players in multiplayer, me and player-X.
We both have the same aircraft installed, F-18A and F-18M (M=multiplayer).
We both fly the F-18A but I see player-X in F-18M and player-X sees me in the F-18M.
That way we can both fly the high detailed version but see the other in the low multiplayer version so to not kill frame rate.
I know this can be done as Vatsim is doing with SquakBox some how.
I know I may have to do it some coding in maybe a program that is ok, I just need a starting point.