First, you'll need a very fast car for this mission. Second, this mission can either be very infuriating or very easy. You've got to ram his car at quite some speed on the side to stun him, then rush out and get in his car. Now this is were it goes either way: if you don't kill him, he'll come after you in another car shooting at you which can cause a lot of damage to your new car, so it might explode. Or you could kill him, but if your cop heat is high, you'll be killed by the cops. If your cop heat is low however, and you kill him, you'll be able to get away no problem with nobody shooting at you. Either way, drive it to the chop shop in South Beach to complete the mission.
You can now buy the shop for $3,000,000. If you have Montana Holdings it will cost you $2,700,000.