Metal cut settings

On an hp3655 Boss laser, what settings of speed, power, oxygen and shop air gives the best output on 16gauge metal. Ive cut bigger signs and had no problem but i tried cutting .5inch size letters and it gets to hot and ends up blowing out the metal. I went up to 1.5inch letters and it would do fine until it got to a turn or ran beside the other cut like on a W and it would distort the cut. My O2 is set about 75psi and compressor is at 60psi with 6 speed and 95 power. Any help would be awesome.