Arctic Silencer Questions

[LeArN2LiVe]

I recently purchased a HIS 9800 IceQ and it comes with the arctic silencer preinstalled. I had 2 quick questions about this product. On the back there is a grill for the exhaust and I was wondering if I should cut this? And there is a toggle for the fan speed and but I can't tell between high and low settings. How do I set it on high?