Well, my shots come out looking like god shots, thick beautiful color, the dark flecking at the top of the crema. About 60ml in 25secs. However they are bitter. I think the problem is although I have PID'd my Silvia I am failing to know how to use it/dial it in correctly. Do I flush a few seconds, let it rebound then fall? The PID came set at 105 and this seems to be what people use in youtube videos of PID'd shots. Something is definitely not right though. The only other thing I have done is put the bar on 9bar via the adjustable opv. The Silvia now fills 250ml of water per min which seems to be the correct volume for 9bar.

What am I doing wrong? Is my PID shot method wrong? shot temp too high? over extracting? Is really a tough one for me to nail this down. Thanks for any help!

tried a looser grind, harder tamp. Wife said it tasted like an ash tray. Think I might have to book into an espresso course, feels like I'm shooting in the dark. I also get steamboil coming out of the group when the machine has been idling at 105 for a while. Is that normal for a PID'd machine idling at 105? That makes me think the heat sensor is not right and the water is too hot? Although I did drop the PID to 102 and tried a shot there and it came out sour which indicated too cold a brew temp.

1 - Try a different basket. The stock Silvia basket is a challenge. The La Marzocco triple, straight-sided basket is a favorite. Bitter can be caused by a number of factors, but a loose rule is if the coffee tastes bitter, try more coffee.
2 - Try a different coffee. Just because it tastes good at a shop on their equipment does not mean it works well on your equipment. If all else fails, try a an of Illy whole bean espresso.
3 - The Rocky is not my first choice in grinders. It allows one, or maybe two clicks for espresso and that is about all. It's tolerances are generally low as well. Do a search for the teflon tape mod for Rocky as it helps and also for the stepless mod (which I think might be same same thing).
4 - Try the "How To" #12 on my website.

Ok, I am making progress! I got a larger basket. I would say it's between a double and triple, a fair bit bigger than the stock double but not quite a big triple. I played some more with my temp probe mounting and seem to now have it mounted exactly as the instructions say so the readout seems fairly stable. Today I pulled my best shot yet and made a flat white, was very close to my liking. There was a very slight brightness to the shot and although the flavour wanted to come on strong it couldn't seem to quite et there. I suspect the beans may be too fresh -but- at this point I had the PID set at 103c and I noticed a very slight flash boil out of the head at this 103 setting. I have now dialed the PID back to 102 and will try this, could be more in the ballpark? Might wait till tomorrow after the beans sit a little longer.

I would try measuring the temprature of the water coming out of the head. 105c sounds like it's in the ballpark for the right boiler temp to get around 90c for brew water, but I'm not sure what the right offset for a Silvia is, and it could easily be off by 2-5 degrees which would definitely cause problems with the taste. And if you're getting flash boiling it sounds like it's set too high. Plus whatever coffee you've got might like a very different temp than what you're using now.

It sounds like you're heading in the right direction by turning the temp down, my advice would be to keep turning it down and pulling shots at 1 or 2c intervals until the coffee starts to taste sour, that way you'll know the range of flavors for this coffee at different temps (it's always good to get an idea of the range). Then just head for the middle, or whatever temp tasted best to you.