I drove through Gabon,Congo,DRC, Angola in June-July with a fully loaded bike 1150GSA - here's a brief summary of the roads - this information refers to the Michelin 746 map. Hope this is helpful to other travelers. -Mike

Gabon Petrol 595/Liter Diesel 470/liter
Liberille->Lope Rough Piste but o.k
Lope -> Lastourville Piste much smoother o.k dry could be slippy in rain.
Latourville -> Moanda: smooth piste logging road.
Moanda -> Fanceville: smooth tar good.
Franceville -> Lekoni: smooth tard good.
Congo: Pterol ??
Lekoni -> Akou -> Edjoua: sand tough going on bike o.k with 4wd jeep.
Edjoua -> Okyo -> Boundji -> Obouya: sand very tough going easy with 4 w.d.
Obouya -> Oyo -> Olombo -> Gamboma -> Brazzaville: Good Tar road
DRC: Petrol 850/liter
Kinshasa -> Matadi: good tar road
Angola: Petrol 40 cents (US) /Liter Diesel 30 cents (U.S) /Liter
Crossed into Angola at Kwhlounhgongo (easy crossing 50KM before Matadi) Piste o.k
Kwhlounhgongo -> M'Basa Congo: good piste
M'Basa Congo -> Cumbi -> Xamindele -> Tomboco: Rough Piste slow going
Tomboco -> N'Zeto : rough piste corrugations broke tar
N'Zeto -> Mussera -> Ambriz -> Caxito: rough broken tar slow going
Caxito -> Cacuaco -> Luanda: Good tar
Luanda -> Porto Ambioim -> Sumbe -> Lobito -> Benguela: very good tar costal road nice.
Benguela -> Catengue: 1st 50 miles good new tar road.
Catengue -> Chongori -> Quilengues -> Cacula: rough piste corrugations, road construction ongoing.
Cacula -> Hoque -> Toco -> Lubango: rough piste corrugations,broke tar, road construction ongoing.
50 miles before Lubango: new tar road great.
Lubango -> Namibe: very good tar road.
Lubango -> Chibia -> Quihita -> Chibemba -> Chama -> Humbe -> Xangongo -> Ondjiva:
Rough piste, broken tar , corrugations, some 10 mile stretches new tar, road construction ongoing.

Ondjiva -> Oshikango Nice new tar road.
Namibia: Petrol 9.82 Rand / Liter Diesel 11.38 / Liter
good tar roads , good gravel roads very very easy!