So no boost gauge and you say it's boosting to 0.9 bar?? How the chuff can you say that with no gauge??? The 3 lights on the dash mean next to nothing in the real world except showing that you are on boost!! The exhaust will be causing it to cut in the colder air recently, You should feel it about to hit cut before it actually does it it will hesitate slightly then if you are a numpty and keep pushing it you get the bang of it cutting the fuel. Get the basics sorted out before you go faffing around with upping the boost.