I build 0.7 coils and don't vape higher than 25w. A lot of it depends on the juice. If your juice has a higher vg content it may not wick fast enough and that's why it's burning. I would try to run it at a wattage before it burns, and just leave it at that. Maybe the problem is the sigelei is just more accurate than your other mod, or there's less voltage loss in the mod itself and that's why it's burning at the same wattage that runs fine on your old mod.