Remove the headers and take them to a local engineering shop and let them drill it out via an over-head drill.
Why? because the hole said bolt screw into is hardened and to successfully drill out the snapped bolt you have to drill precisely in the middle of said bolt. If your off-center even a little, as you go up in drill bit sizes you will eventually get the point where the edge of the drill bit will meet the threaded edge of the 6mm hole in the headers. A) you will possibly damage said thread and B) there will still be too much of the old stud left to realistically remove it and C) if you fuck it up you wont be able to put a timesert or helecoil in due to the hardened metal etc.
Do it right, do it once and when your done replace those 3x m6*10mm bolts with titanium replacements -
- http://www.ebay.co.uk/itm/Ti-Titanium-M6...1049602623
Why? because the hole said bolt screw into is hardened and to successfully drill out the snapped bolt you have to drill precisely in the middle of said bolt. If your off-center even a little, as you go up in drill bit sizes you will eventually get the point where the edge of the drill bit will meet the threaded edge of the 6mm hole in the headers. A) you will possibly damage said thread and B) there will still be too much of the old stud left to realistically remove it and C) if you fuck it up you wont be able to put a timesert or helecoil in due to the hardened metal etc.
Do it right, do it once and when your done replace those 3x m6*10mm bolts with titanium replacements -
- http://www.ebay.co.uk/itm/Ti-Titanium-M6...1049602623