I've had the Silvia for ~6 mnths and from advice gleaned from various helpful websites I've ended up with the setup and practice that Colin describes in his article on the Silvia. One outstanding issue remains uncertain; the tamping pressure. Some say high, some say low. I'm wondering if tamping pressure cannot be discussed without also discussing the grind. The goal seems to be pull a shot in ~25 seconds. Could one do this with a coarser grind and 30lbs of tamping pressure or a finer grind and 15lbs of tamping pressure? Are these equally valid? I'm asking the question for a specific reason. I recently had the best cappucino I've ever had in West Victoria BC. I bought their espresso and made some at home. The result wasn't even close to what they served. I'm using distilled water so that didn't help (according to Colin). My attempt was much more bitter. I think the issue may be the tamping/grind.
Never, ever use distilled water for coffee brewing.
The results will be remarkably bad.
Use tamp pressure to regulate the flow of espresso into your cup.
Grind your coffee fine enough that you only need 5 to 10 pounds of pressure - if that.
Remember this - they do not tamp like crazy people in Europe.
We (North American's) created this obsession of tamping till our forehead veins burst.
It is utter nonsense and contributes nothing but repetitive strain to our physical condition.
25 seconds is a nice number - but it should not be cast in stone.