I was wondering what you mean by resolution 4 or resolution 2 for textures ...
Oh you now, it's when you put a number multiple of 2 after a texture on the load.ini. Like this :
[FIELDS]
LowLand0 = redko_tex/lybia/redkolybia1blend_fields.tga,4
LowLand1 = redko_tex/lybia/redkolybia3blend_fields.tga,4
LowLand2 = redko_tex/lybia/redkolybia80_fields.tga,4
LowLand3 = redko_tex/lybia/redkolybia40Cblend_fields.tga,4
MidLand0 = redko_tex/lybia/redkolybia73.tga,4
MidLand1 = redko_tex/lybia/redkolybia76.tga,4
MidLand2 = redko_tex/lybia/redkolybia84_fields.tga,4
MidLand3 = redko_tex/lybia/redkolybia85_fields.tga,4
With 2, the size of the texture is 2 times smaller on the ground, with 4 it's 4 times smaller. The more the texture is small (if you keep fixed the resolution of course) more precise and detailed is the texture. So you can consider that the texture is twice or 4 times higher in resolution.
It works well specially with 1024x1024 textures. More the texture is detailed, more it's nice for low flight. The bad point is that as the texture is smaller in the ground, you have to work twice to paint all th map. It takes twice time but it deserves it.
For Desert_Online i started at 4 for each texture, but there was to many repetition (that the second bad point of higher resolution) so i decided to mix 2 and 4. so now the result, Desert_Online and SandsOfTime are pretty nice for low altitude flight. But these 2 maps are in a way the bastard of Lybia repaint...a map I started at resolution 4 for each slot. The melting was not god enough to keep this, too many repetition too. So i decided to mix 2 and 4...and then i started with the repaint of Desert and Sands which are released now.
For Mto, i progressed a little bit more with the texture, and the melting is good enough "for the moment" to keep all in resolution 4. You can fly low and the rendering is nice, very detailed, but without repetition.
That's why i'm testing the map with a gladiator, it's a slow plane, you can fly slow and low to catch every single detail.
For exemple, for the texture you are using in Djibouti map for the city ground, i would use it with 2 or 4. The granular effect will be nicer improving the low flight over the city. As you map is big, i would use a mix of 2 and 4 resolution. It's somthing you have to test to your like, it's not easy to know where to use 2 or 4, or more but personally i won't use normal resolution anymore, except for the shallow waters i guess.