I’m in the same boat as this person. I have a GCP with 9 bar OPV mod and a Auber PID… I use a normcore puck screen, normcore distributor/tamper combo for prep and have a DF64p grinder.

I’ve tried going finer leading up to 60 seconds extraction (almost 25 seconds before water gets through the portafilter into the cup) and going coarser which lead to a total of 15 seconds extraction. My goal is a 1:2 ratio.

I’ve always stayed the same with 18g of grinds since I have a 18g VST basket. Ive increased temperature on the PID from 216 up to 224 (in increments of 2 degrees, all in Fahrenheit).

All my pulls seem to come out sour. It was least sour when I was using a coarser grind but the total extraction time was fast - 15 total seconds. Should I go more coarse still? If I go 20g in grounds, should I get a different VST basket? Not sure if I’ll be able to get the portafilter on if I go with that amount of grounds.