That's outstanding Christoph, those quantitative scores are stratospheric. I'm a native New Yorker who reads the Economist and Financial Times religiously (both British publications), and agree that they are probably the best material to read to sharpen your critical reasoning skills, because they are so well researched and tightly written.
One note of caution, though, for those that use them to prepare for the GMAT, is that you have to be careful not to pick up their idioms and pronoun usage, which are (slightly in the case of the Economist, moreso in the FT) different than the canonical American uses that show up on the test. I realized that I had picked up British grammar over the years, and was getting some Sentence correction questions wrong because of it.
Anyway, outstanding on your part. Best of luck!