Before starting Sweets mission Los Sepulcros (roughly 25 missions into the game), where you have to kill a gang member named Kane, get a 2 star wanted level. It will not disappear without going to pay and spray. Progress with the mission to where you kill Kane. At the cemetery, cops will spawn, but not attack you. After taking out all the Ballas + Kane, DO NOT enter the car with Sweet. Instead, start killing the random cops that spawn. They drop pistol ammo, so you will not run out. A LOT of cop kills later(40+-), you'll eventually get the 6 star, then you can enter the car with Sweet, and "try" to get back to Grove Street. Good luck because there are tanks that will blow up your car in 1 hit. If you die, you'll restart at the cemetery with your original 2 stars. Just redo the mission, avoiding the cops, and race home on 2/3 stars.