I have to say it, sorry but it still looks bowed to me. I had a similar problem back when I first started in 2010 and at that time I slowed the print speed down to 40mm/s instead of 60 and it fixed my prob. I've since changed firmware to Repetier and I've not had the problem since even at 60mm/s, I was using Sprinter and have gone through using Marlin ok too.

If you can't fix it in firmware try playing with the settings in your slicer but keep a note of what your changing, there's nothing worse than altering your settings, finding it doesn't work and you've forgotten the original settings.