thanx for d replies guys. will get d belts checked out etc. and i dont think its the gearbox, because the noise can also be heard by reving it hard in neutral before taking it for a drive. im hoping its a belt. and as for mods, i got:
Apexi pFC, bosch 044 pump, z32 afm, 3" turbo back exhaust, arc filter, fmic, hks evc3,
also, if it was the turbos bearing i dont think the noise would go away after a while. think it might be either a belt, or possible throttle related as sumone pointed out. will look into it asap. any more ideas would be appreciated.
thanks guys