p.45 of the main rulebook, bottom right:
- Eldar (and Dark Eldar) Jetbikes - "...jetbikes may move up to 2d6" in the Assault phase..."
and then just above it, top right:
- Turbo-Boost - "...jetbikes therefore cannot shoot, charge, or execute any other voluntary action for the rest of the turn after turbo-boosting."
So since turbo-boosting happens before the assault-move, they can't do it.
And yeah if a transport moves at speed X, the passengers are always considered to have moved at speed X as well.
I dedicate these deaths to Odin Allfather, Spearshaker, One Eye.
Fleet Shadowmaker - Kabal of the Dying Sun; Cult of Marrow Excised; Coven of Lambent Hunger
Sons of the Last Breath - Chaos Space Marines
Host of Shattered Purity - Chaos Daemons