this setpos [(getpos this select 0), (getpos this select 1), + 6]
uhm...i thought OFP uses [x,y,z] coordinates to place object so your example would move the object along it's east/west angle.
Shouldn't it be:
this setpos [getpos this select 0, getpos this select 1, (getpos this select 2) +/-5]
so this select 0 stands for north/south angle
this select 1 stands for the east/west angle
and this select 2 stands for the up/down angle
unsure about it but check it plz