The GTA IV mission "The Cousins Bellic" in GTA SA.
You should download these mods or the mission will not be good.:

GTA IV TO SA TC (MUST DOWNLOAD OR THE MISSION WILL NOT WORK!):
http://depositfiles.com/ru/files/f3ynya8r9
(Password: nikobellic01)
Roman ped:
http://www.gtagaming.com/downloads/gta-san-andreas/player-mods/5184
Niko bellic stories:
http://www.mediafire.com/?zzhjwzmyimm
Roman's taxi:
http://www.gtainside.com/en/download.php?do=download&id=22157

And then the mission will work like a charm.

Credits to:
*Vans123 and Rwils79 for GTA IV TO SA TC.
*Marklez White for Roman Ped.
*Masterod for Niko Bellic Stories (Niko bellic Ped and marker)
*Automan for Roman's Taxi
*And ofc Rockstar games for the beautiful GTA SA !

ENJOY !