20 grams in, 40 grams out 25 to 30 seconds brew time, remember that once you have good coffee and water, distribution is probably the most important part dialing in good espresso, grind size can be adjusted to get the right brew time and amount but if channels or edge cracking occurs improper extraction will cause sour or bitter taste, using a Distribution tool can help, tamping is less important and consistency is key.

Here is a link to a distribution tool that works well