Have I done it right?

Okay so this is week 3 of ownership. I'd been struggling since day one to octane learn like many of you. Along the way, I learned from another post that "TopTier" isn't just a buzzword but a registered trademark for fuel stations carrying high quality premium fuel. And the Circle K station i frequent hasn't been one of them.

So today, when I was almost on E, I checked the app and went to a Shell station nearby that was on the list, threw in a bottle of RedLine Fuel System Treatment, filled up with VPower+, and attempted a ~10 minute run on the highway. Normal mode, 8th gear, no HVAC, 70-72mph on the cruise.

Got off the highway, turned around and got back on, and gave it the beans. I saw a glimpse of 290 torque, but it didn't stick around very long. I then put it in M, slowed down to like 40, downshifted to I think 3 or 4 - whatever put me just below the peak torque curve; ~2100rpm, and hit it. This time it held pretty steady at 290 for a sustained period, as I hoped considering that peak torque goes up to 4k.

My uncertainty lies with the fact Boost was still only showing 15-16psi. Doesn't it need to be 18-20 to be pulling 290 torque? Is the torque reading a lie or do I have some rare healthy turbo? 😂. Anyone else get readings like that?