To find a Yardie Lobo, head to Newport on Staunton Island. A place to find them most often is near where you get the missions from Asuka. She will be living in an apartment block near the blocks. There will be a bridge area above. Along this road is where you will find the Yardie gang car.
For more information on Newport, you can check out the GTA wiki entry for newport http://gta.wikia.com/wiki/Newport