on mY00 Turbo sometimes floor it in 2nd gear and boost only goes up to 0.5 but only in second my mates has done the same any ideas but its only done it when cars not really been running long didnt know weather it was a safety boost cut

Drive by noise test compliance by design. Entirely normal.

can somebody explain

I just did. It is designed that way to pass a noise test required by law. It is normal.