Glad your Yildiz is shooting great. or do something with the chokes to change where the gun shoots. I don't know much about the second option, does anyone know what they would do? I don't think I would want them to make it shoot special chokes, because it seems that would render all my factory chokes useless.
I believe what the 2nd option entails is actually re-cutting the threads for the factory choke tubes, but in a slightly non-concentric manner. So, the choke tubes are pointing in a very slightly different direction than the bore. This slight deviation gently alters the trajectory of the shot, so that it will impact to the same point of aim as the top barrel (or at least close enough that it's not readily apparent).
I guess it would depend on how far "off" your bottom barrel is from your top barrel on whether or not they could do this. If it's like a foot low at 30 yds, I would think this could fix the problem.