Hi Thanasis, I've talked with him also and he told that when the engine is cold oil pressure is at 8-9bar at idle, when it gets hotter pressure drops at 3,5bar and when engine is at normal operating temperature drops at 1bar at idle (1000rpm). When he accelerates oil pressure rises again and at idle drops back again at 1bar.
He has installed a complete Titan dry sump kit, with oil tank(boot), external oil pump ect...
He has tried many oil types and results are the same!
The engine has been rebuilt recently, works fine and as smooth as possible (because of camshaft overlap)