I purchased a new OPV that I believe to be of better quality than the one installed in my brewtus II.
Based on info I found on the net , i tried to source the proper parts. Just for reference,you can see here what I sourced (I did not purchase from them): http://www.bellabarista.co.uk/coffeespa ... 279&cat=34

With that installed in series with the pump I now have reading on my dial of 7.5 bar with the rubber blind filter and 6 bar when brewing...but with a grind setting that used to produce 10 to 11 bar of pressure.
The taste is harsh so i believe it is actually brewing at 10-11 bar.

The machine manometer is connected to the top of the brew boiler.
Did I introduced air in the system or did anything wrong as to damage something unintentionally?
Is there a special procedure to purge the excess air if that is the problem?

Why not simply adjust it up to the same value you had with your previous OPV? It would be a rare occurance if a purchased OPV was adjusted "just right" out of the box.