Just to reiterate what Jinx has said..
These are IMO good value for money guns and work well out of the box. Most 'mods' that have been done are ,again IMO, done mainly for comfort and aesthetics such as mine.
The shroud has been milled but not for any POI issue that has been discussed but purely so I could fit the UK Neil air stripper that I got for it, the only other mod I've done is have a butt hook made by Norris ( top man on a lathe ) with some longer spacers to accomodate my 17.5 inch LOP !!.
The internals are all standard.
On a new one you may find the cocking stiff at first, again this has been well documented on this and other forums and you can either take the arm out and 'polish' it or it will loosen up with use.