As soon you take control of Trevor in the game grab yourself a car (mine happened to be a cheval fugitive sedan) and take it to the customs shop. Trevor has a rack full of money from the off so customise everything! The achievement will pop when you leave the garage. If it doesn`t head straight back in and check you brought everything you need... NOTE: you don't need to buy the most expensive upgrades any will do and also some cars don`t have spoilers to upgrade or a hood to change etc so as long you do the maximum to the vehicle your in this will not matter...
CHECKLIST:
Armor
Breaks
Bumpers (some cars don`t have this upgrade option)
Engine
Exhaust (some cars don`t have this upgrade option)
Hood (some cars don`t have this upgrade option)
Horn
Lights
Plates
Re spray Primary
Re spray Secondary(some cars dont have this upgrade option)
Roof (some cars don`t have this upgrade option)
Skirts (some cars don`t have this upgrade option)
Spoiler (some cars don`t have this upgrade option)
Suspension
Transmission
Turbo
Wheels
Wheel Colour
Wheel Accessories - bulletproof tyres and smoke.
Windows
Hope this helps...
