I'm not volunteering, but for fun I tried to beat my record today. And I beat it!
Well, only by one character ;-) My old record was 630 characters per minute, and my new record is 631 characters per minute, so it still calculates as 126 WPM.
I'm having difficulty improving now, which is not surprising since there is no longer any specific weakness in my typing. Rather, there is a wide range of little weaknesses which I can only improve on gradually.
However, it makes me thing I should revisit the idea of adding statistics to the test which can point out your weakest words, letters and letter combinations.