Ok then mate, Outside air temp makes a big difference to performance, If it was cold you will have felt the car being "faster", as the air is much more dense and will give slightly better power. What boost is it running? As On my small turbo, I had problems last year as in the daytime it was fine (remember the heatwave?!) , but at night it would overboost slightly, and do exactly what you said, like hitting a brick wall. Does the car stop boosting fully after that? I used to have to turn my car off and on again to clear the overboost from the ECU.

I know it has just been set up, but was it a hot day when it was?

Another thing to check is the security of the Chip module into the back of the ECU, ( passenger side footwell behind the fuel cut off Kick panel, again, I had an MSD chip module that had been in the car for some time, and over time had worn the ECU contacts away a bit, and would cause misfires as it made and broke contacts.... Way to sort that is to re-solder the ECU contacts on the board to make them a bit thicker, as Stu checked the module and replaced my chip contacts for free (even though the chip was two owners old ,) , but the problem seemed to be the ECU contacts as it did it again afterwards