Need for Speed
45 Achievements
Full Power
Equip top end performance parts to each category of a car
How to unlock the Full Power achievement in Need for Speed - Definitive Guide
The top end parts are all the orange E performance parts, there are 21 different parts that you will need to equip. From what I can tell the parts cost about the same no matter how expensive the car so pick whichever you want. You will likely be upgrading as you progress so you wont notice them costing a lot.
You might earn some free parts from the pickups around the map though the highest one I got was a top level Forced Induction which is unlocked at REP level 40 anyway.
Here'd a video showing each part upgraded
To unlock these parts you need to hit two requirements.
1) You need to be level 50 and so unlock this trophy:
2) You need to have completed the story missions for Amy, these are the purple build missions. The last mission for Amy unlocks:
Once you have unlocked all the high end parts just purchase and equip them to your car. If you're short of funds sell any spare cars you have. I found the trophy unlocked when I exited the garage.
You must purchase and equip the last unlockable performance part for any car for all 21 car parts as follows;
-Air Filter
-Brakes
-Cam Shaft
-Clutch
-Cooling System
-Cylinder Heads
-Differential
-Electric System
-Engine Block
-Engine Control Unit (ECU)
-Exhaust Manifold
-Exhaust System
-Forced Induction
-Fuel System
-Handbrake
-Ignition
-Intake Manifold
-Nitrous System
-Suspension
-Sway Bars
-Tyres
A top end performance part is distinguished but its "E" for Elite stage performance part. You must progress through REP levels and complete all of Amy's story missions to unlock all Elite performance parts. The last performance part (Engine Block) is unlocked at REP level 50.
See "Can I Get Your Autograph?" for more details on how to quickly earn REP.