Maybe the guys from Euro Compulsion can tell us at which RPM the 2.0 crosses the boost threshold.
If I had to guess I’d say it’s around 2,000 RPM.
On my last car (2007 A4) it was around 2,500 RPM, based on the seat of my pants boost guage.
These two things are often confused. I hear people talking about lag all the time, when what they really are complaining about is power below the boost threshold. It's tough to pin down a specific RPM because of the slightly different definition. Is it when the turbo can create full boost, or meaningful boost, or any boost? It's quite low in our car, and I'll say that 2000rpm is a good number for a stock 2.0 Giulia.
My DD is a 535 xi Touring Wagon. Manual states that stock it puts out 300 torque at 1400 rpm. The CR is 10:1, so there is no "turbo lag". Mine has the Dinan Stage 2. HP at 375 and Torque at 415.
The concern may date back to the initial days of turbocharging. Porsche was early in development and with the heat transfer problems of air-cooled engines the CR was as low as 7. It took a while to spool up and there was lag.
Subaru did a lot for turbocharging, but their WRXs had 8 to 1 CR.
Today's turbo engines have no "lag" and develope remarkable power from, for example, the Giulia's 2 L.