Yes, it's normal for your boost gauge to read 1.8 bar at full boost for a factory stock setup. Mine certainly does.
I think the confusion might come from what the boost is read in reference to. In the 951, "1 bar" on the boost gauge means that the manifold is at the same pressure as the outside air (about one bar). Some other cars have the boost gauge set up so that 0 is the same as the outside air, less pressure in the manifold is read as vacuum, and more is boost.
I think when AaronM says set the boost for 15 psi, he means 15 psi over atmosphere, which would read a little over 2 bar on the 951 gauge.