The standard path
- Ditch the stock pressurized basket for a non-pressurized 58mm basket; Gaggia's own unpressurized baskets or any commercial double works
- Precision baskets (IMS, VST) in 18g capacity are the enthusiast staple and fit without any adapter
- Pair with a 58mm bottomless portafilter, universally available because the size is the commercial standard
Why 58mm matters here
Machines with proprietary group sizes trap you in narrow accessory ecosystems. The Classic Pro shares its basket size with commercial machines, so decades of accessories, tampers and distribution tools fit. Accessories you buy for it survive any future machine upgrade to a prosumer 58mm machine.
One practical note
Deep 18g baskets plus a fine grind demand more from your grinder than the stock pressurized setup; make the basket switch when you have a grinder that can produce true espresso range. Otherwise shots will run fast and thin, and the basket will take the blame unfairly.
The order the mods want to happen in
The community's decision path for this machine is unusually settled. A grinder that can produce true espresso-range grounds comes first; nothing downstream works without it. The switch to a non-pressurized 58mm basket comes with or immediately after, and the OPV pressure adjustment pairs naturally with that switch, since the factory pressure is tuned for the pressurized basket. A bottomless portafilter follows for feedback, and precision baskets from IMS or VST come last, as refinement rather than repair. Owners who buy in the reverse order, precision basket first on a blade grinder, generate most of the frustrated posts. Each step makes the next one's effect visible, which is the point of sequencing.
Checking clearance with deeper baskets
Standard doubles seat with room to spare, but the deepest high-capacity baskets deserve one check before you commit to a full dose. Prepare a puck as usual, rest a small coin on the tamped surface, lock the portafilter in, then remove it and look: a coin pressed into the coffee, or a screw imprint on the puck's face after a real shot, means the dose is too tall for the available headspace. The fix is a lighter dose or a shallower basket, not force. This matters more as capacity climbs past standard doubles; in normal 18 gram territory the Classic Pro's group takes it without drama.
What changes in the cup, honestly
Expect the crema to get thinner and darker, not thicker. The pressurized stock basket whips up a tall, uniform foam regardless of coffee quality; the non-pressurized basket produces real crema, which is subtler and varies with the beans and roast age. Under it, the difference is large: sweetness and origin character replace the somewhat generic, hollow taste the pressurized basket makes from any grind. Owners also report shots become less consistent at first, because the basket now transmits every prep mistake, then more consistent than before once grind and distribution settle. If a shot gushes early on, the basket is reporting the grind, not failing.