Engine basically starts/idles/runs very smoothly, but it always starts to 'roar' from 3500 rpm and upwards. Everything else seems to be okay, so I was thinking to have the timing checked. From what you write, however, perhaps there's no point in doing that as the timing is electronically controlled, except for the vacuum line.
What do you think?
'01 DT41 - M54 - A5S 325Z - 482