First 100km no more than 3krpm no boost or minimum actuator/ wastegate pressure using running in oil. Then 500kms of varying load slowly introducing more revs and more boost getting closer to a maximum 5000rpm and 14 psi as you get nearer to the 500kms mark.

After that 500 I'll drop the oil change the filter and go fully synthetic. Time for tuning and proper boost then.

I've tried the gently gently approach several times and the engines I ran in that way always seemed to use the most oil.
The method described above has served me well over the years and oil consumption has been minimal.

Considering 2.5s are notorious for oil consumption I've just had to top mine up for the first time in about 3000 kms where it needed just over half a litre to bring it back to the full mark. That's with daily driving and seeing 1.7 bar on a regular basis. I think Subaru deem anything more than 1 litre/1500kms needs looking at.

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605whp
Quarter Mile in 10.9 seconds @ 135mph /217kph
0-100 kph 3.2 seconds